|Red oxide of Manganese||87·0||72·5|
|Sesquioxide of Iron||1·3||4·2|
The native binoxide often contains both copper and cobalt in addition to iron; frequently to the amount of as much as 1 per cent. of copper and about ·54 per cent. of cobalt.
Wad, a native binoxide of manganese, sometimes contains 54·34 per cent. of iron, while nearly all the manganese ores contain more or less alumina, varying from ·5 per cent. to as much as 20 per cent.
From the composition of ordinary commercial black oxide of manganese, as shown by these analyses, it is evident that it is better to use the pure article, and this has been found to be the case by the firm who have adopted it in lieu of commercial black oxide of manganese. I therefore strongly recommend all glass makers to try and experiment with it, for the results obtained will largely counterbalance the extra cost of the pure material; and I also much doubt whether the same injurious effects will be produced on the pots, as is the case where commercial manganese is employed.
Arsenious acid also acts as an oxidizing agent, in that it gives up its oxygen to the protoxide of iron, converting it into the peroxide; but the arsenic itself, which has lost its oxygen, is reduced to the metallic state, and being volatile, does not remain with the glass, but passes off by the flues of the furnace. If too much arsenic is used, it sometimes renders the glass milky or cloudy.
Before describing in detail the method of mixing and founding glass, it will be necessary to mention the composition of the vessels in which the glass is made. They are called glass-pots, and differ in shape according to the different kinds of glass to be made in them. Glass-pots are made of fire-clay (generally the best Stourbridge), which is a silicate of alumina, and here great care is taken to select that which contains least lime or iron. It is ground, then moistened and well kneaded together, and left to ripen, while a certain quantity of old glass-pot is ground fine and mixed with the fresh fire-clay. Masses about the size of two hands are kneaded separately, the object being to exclude all air bubbles, and to obtain a perfectly homogeneous lump. The bottom of the glass-pot is then laid, the masses of fire-clay being pressed in with the greatest care, so as to avoid all cracks or places where air might enter during the slow process of drying.
The modern shape is round; though formerly certain glass-pots, called cuvettes, used in the purifying of plate glass, were square. Pots used in the manufacture of common crown and sheet window glass, generally speaking, are larger at the top than at the bottom; but whatever may be the shape of the pot, the method of its building is the same. The sides are carefully made of fire-clay, each piece being laid on by itself and kneaded like the bottom of the pot, so that it is slowly built up until it reaches the desired height. It is then dried very gradually, and the process is finished in artificially warmed chambers. Before putting it in its place in the glass-furnace, it is allowed to remain for some time in what is called a pot-arch, that is, an archway built of fire-clay bricks, along the side of which is a fireplace, by means of which the arch is brought up to a red heat; and after it has been heated sufficiently, is removed while red-hot and put into the furnace. Glass-pots are never allowed to cool, and with care they may last for several months. From this description of their manufacture, it will be clear that it is attended with considerable cost, varying from 5l. to 10l.
There are three different kinds of ordinary pots for crown, plate, and flint glass; and of these the last is decidedly the most expensive, as its top is covered over, and presents the appearance of a dome with an opening in front, through which the materials can be introduced when the pot is charged, and from which, when made, the glass may be drawn, in order to be blown into shape by the workman. In glass-furnaces the pots are sometimes arranged in a circle, with their mouths opening into the glass-house; but now a different construction is sometimes employed, since other methods of heating the furnaces have been introduced. It is hardly within the scope of this article to enter into a description of glass-furnaces; suffice it to state, that they should be of such a construction as to yield the greatest amount of well-regulated heat for the smallest consumption of fuel, and this object seems to be best effected by the adoption of Mr. Siemens' excellent principle of heating furnaces. For some years his process has been in use at the Thames Plate Glass Company's Works, where the saving of fuel has been very considerable, and the glass greatly improved, owing to the fact that impurities from the fuel employed cannot possibly find such easy entrance into the glass-pot. In any case, the construction of the furnace is such, as to be best adapted to the convenience of the workmen, according to the kinds of glass which they have to make. Differently arranged furnaces are used for bottles from those employed for crown and sheet glass.
It has lately come to my knowledge that flint glass, that is to say, the glass used for tumblers, decanters, and such like, is occasionally injured by the appearance in it of little opaque white spots. Some portions of glass of this character have been analyzed by me, when I found that these white spots were owing to the presence of a glass containing alumina. Now alumina raises the melting point of any glass of which it is a constituent. So, then, these white spots were due to the presence in the flint glass, which was perfectly clear, of a much less fusible glass which was only partly made when the flint glass was ready for working. On investigating the matter, it was found that the alumina came from the glass-pots, for when by my advice the faulty pot was withdrawn from the furnace and carefully examined, although it had been in work only six weeks, the bottom was honey-combed to a very considerable extent, showing that portions of the pot had been dissolved; and inasmuch as the fire-clay, of which the pots are made, contains a large quantity of alumina, it was not difficult to trace the source of these white spots which had rendered useless much very valuable glass. On inquiry it was found that the pots had been made entirely of new clay, and on reference to the book of workings, which was kept in the glass-house, it was also found that for some time, the glass-pots used in that establishment had been made of new clay, and that on a previous occasion a similar calamity had before happened.
In the records kept where pots were made, as has already been described, with a portion of old pot as well as new clay, no white spots had ever appeared in the glass. It is therefore manifest, that it is much safer to use a portion of old pot than to trust to pots made entirely of new clay.
Having considered briefly the manufacture of glass-pots, I shall proceed to the treatment of the materials to be employed. In making common window glass, ordinary sand, which does not contain any very large quantity of iron, may be used, the alkali employed being sulphate of soda, while the purifying material is either arsenic or black oxide of manganese. A small quantity of anthracite coal is added to the mixture, in order to assist in the reduction of the sulphate of soda, together with some lime. The materials are carefully mixed and placed in the furnace, where they are heated for some time, a process which is called "fritting." Its object is to perfectly dry the materials, so as to expel carbonic acid gas, which would otherwise cause swelling in the glass; but no combination must take place, to allow of silicates being formed, otherwise the alkali would melt first and attack the substance of the glass-pots, and part of it would be volatilized and lost. When this operation is completed, the fritt is put into the hot glass-pot, and submitted to the action of the heat of the furnace, until the glass is made, or "founded," as it is technically termed. In the case of sheet and crown glass, this process lasts from sixteen to seventeen hours, for it will be remembered that the top of the pot is open to the furnace, so that the flames pass over the surface of its contents. In this way the materials get heated more rapidly than when a covered glass-pot is used.
M. Gehlen gives as a good mixture for window glass:
|Dry sulphate of soda||50||"|
|Carbon, as charcoal||4||"|
Different makers have different mixtures. This by M. Gehlen is given as about the proportions of the several constituents employed.
The charging of the pots is conducted in this manner: they are filled with lumps of fritt, and the heat of the furnace is raised as rapidly as possible, until, in about eight or nine hours the fritt has run down or melted into glass. More fritt is then added, which also melts, and from time to time this is repeated, till the pot contains a sufficient quantity. After about sixteen hours the whole has become converted into glass, and the surface of the molten mass is covered with liquid salt and sulphate of soda. This scum is called glass-gall or sandiver, and is carefully removed with iron ladles. Some broken glass, or cullet, is now thrown into the glass-pot, a little at a time, the object being to cause any salt which may remain in the pot to rise to the surface, which is then removed, and so the glass is in this manner purified, after it has been further heated for some hours, to expel gases.
When the glass is made, and its temperature so reduced that it is in a doughy or pasty state, it is then worked off by the blowers into either sheets or tables, as is desired. The blowing of sheet and crown glass is a work of considerable difficulty and labour, and one which cannot be successfully performed, except by a workman who has been brought up from boyhood in a glass-house. A quantity of the soft glass is collected or gathered on the end of a blowpipe, and the workman then blows into it, and distends it into a globular form. Now it is necessary, in making sheet glass, that that globular form should be elongated; the workman therefore holds his blowpipe, which is about five feet long, in a vertical direction, and the softened globe becomes pear-shaped. By dexterously swinging the blowpipe from side to side, which he does while standing on a plank placed over a sort of pit, and by causing it to rise on either side, he converts the pear-shape into a true cylinder, having rounded ends. When the cylinder has assumed the exact shape desired, he places his thumb on the end of the blowpipe, and holds the opposite end of the cylinder in the mouth of the furnace. The glass softens at the heated end, and the expanding air causes it to burst the opening. It is then shaped with a suitable tool, so that it is of the diameter of the cylinder. When the latter is cooled, a piece of hot glass is applied to its shoulder with a pontee, and is drawn out into a thread around it. This makes the glass hot. The thread of glass is removed, a cold instrument is applied rapidly, and the shoulder of the blowing is cut off. The glass is next detached from the blowpipe, and its ends removed, and it is then annealed for a short time, and cut down lengthways internally by a diamond. It is afterwards placed, with the long cut uppermost, in what is called a flattening kiln, that is, in a sort of oven or furnace heated to a high temperature and having a perfectly smooth stone floor; after a short exposure the glass softens, and a workman, with suitable wooden tools, opens it out where it was cut by the diamond, and causes it to lie flat upon the stone. It is then rubbed by a wooden tool, and in this way is flattened, removed from the flattening stone kiln, and placed in a hot chamber, in which it is allowed to cool slowly, for the purpose of "annealing."
Sheet glass, formerly called broad glass, was originally made on the Continent; but its manufacture, first established in this country by the introduction of foreign workmen, has extended to very large dimensions, and the quality of English sheet is now quite equal, if not superior, to anything that is produced abroad. The advantage which it possesses over crown glass is, that much larger sheets can be made, and this is very easily noticed if we examine the larger dimensions of common window panes compared with those which were formerly made. Even now the workmen employed in this class of manufacture are generally Belgians. A sheet glass blower must be very strong, and have great skill in handling his blowpipe, for the cylinders which he blows are frequently sixty inches long, and their weight is very considerable. Glass shades are blown by sheet blowers. These sometimes are very large, and require great skill. When their shape is to be that of a cylinder with a dome top, they are made as in the ordinary course of blowing a cylinder of sheet glass, but instead of one end being burst as described, they are simply detached from the blowpipe. When they have to be oval or square at their bases, they are blown into wooden moulds of the required form, which have their insides charred. The gathered mass of glass is placed inside such a mould, and is then blown into until it touches the sides. This is an operation requiring great strength and delicacy; strength to blow with sufficient force to bring the softened glass to touch the mould in all its parts, and delicacy to prevent the pressure from being so great as to cause the outside of the glass shade to receive marks on its surface from the mould.
The shaping of the molten glass into tables of crown is different in detail. The globular mass formed by the first blowings is held by a workman vertically over his head. An assistant gathers a small quantity of soft glass from the furnace on the end of a pointed iron rod, and causes it to adhere to the flattened surface, at a point opposite to that to which the blowpipe is attached. The glass near the blowpipe, while hot, is touched with a cold instrument, and immediately cracks around its neck, detaching the blowpipe from the mass. The pointel is taken by the blower, and the opening formed by the removal of the blowpipe is placed opposite to what is called a "flashing" furnace, that is, a furnace with a large circular opening in its front, and which is heated to such an intense degree, that it is impossible for a person unaccustomed to it to approach within several feet of the furnace-mouth. The workman generally wears a shield or screen to protect the upper part of his body and face. The glass becomes softened by the heat, and the workman gives his pointel a rotary motion, somewhat similar to that which a housemaid gives to a mop when she trundles it; and as the glass softens, the opening gets larger and larger, until at last the softened mass instantaneously flashes out into a circular sheet, an operation which produces a very startling effect upon the eyes of anyone beholding it for the first time. The circular crown table thus made is detached from the pointel, and the mass of glass which caused it to adhere forms what is known by the name of the bull's eye. The table thus made is, like the sheet, placed in an annealing furnace, and there left for a proper length of time.
The manufacture of plate glass is altogether different from that of crown and sheet. First of all, much greater care is taken in the selection of the materials, the sand used being of a purer kind than that employed in the manufacture of common window glass; the alkali is of a better quality; and more caution is taken in all the manipulative processes prior to the melting of the mixture. Arsenious acid is more frequently used than manganese for the correction of the iron impurity. It has been noticed that in the plate glass-pots, there are grooves placed around their sides, and these are intended to receive metal claspers, by means of which the pot can be removed bodily from the furnace. In former times the glass was made in large pots, and then ladled out into smaller ones, of a square form called cuvettes, and in these it was left exposed to the heat of the furnace for a length of time, in order that it might be refined, by the rising of impurities to the surface and by the escape of air bubbles. The use of these cuvettes is now discontinued, and the pot in which the glass is founded is removed from the furnace and its contents poured upon the tables on which the plate is formed, by the action of rollers. A plate glass table is made of iron; its surface is smooth and of the size required to make a large plate, and it is placed upon wheels and run upon a tramway from one part of the glass-house to another, so as to be opposite to the mouth of the furnace from which the glass-pot has to be removed. Along the sides of this table, taken lengthways, moveable strips of iron are placed, rising above it to a sufficient height to secure the desired thickness for the glass plate, and on these strips runs a roller, so adapted that it can be made to pass pretty readily from one end of the table to the other. The contents of the glass-pot, when placed over the table by means of a crane and tilted up, fall out somewhat as a lump of dough would fall from a kneading trough if it were inverted, for it must be borne in mind that the glass in this process is not in a very fluid state. The roller is made to pass rapidly over the softened glass, and in this way spreads it over the table, until it comes in contact with the strips placed along the edge, which serve as gauges for determining the thickness of the plate. After the plate is formed, it immediately sets, and is removed while hot into an annealing furnace, which is always so placed that the glass can be transferred to it from the table with the least possible delay. In this furnace several plates of fresh-made glass are deposited, and are allowed to cool extremely slowly, in order that the glass may be properly annealed. When this process is completed, the plates are removed, the edges are trimmed off with a diamond, and one plate, bedded in plaster of Paris, is placed upon a flat stone receptacle; another plate, also coated on one of its sides with plaster of Paris, is made to adhere to a piece of machinery placed directly above the other plate, and is so situated, with respect to this latter, that the two surfaces are perfectly parallel one to the other.
It should be here mentioned, that the side of the plate which touches the table is always rough, and has no polish, while that over which the roller is passed is slightly undulating, and has a bright polish similar to that of a sheet of blown glass, and which is technically known as "fire" polish. The machine to which the upper plate is attached is so arranged that, when set in motion, it causes it to move in just the same direction that a plate would do if moved by the human arm; this is therefore called an elbow motion. Boys stand by the sides of the two plates, and throw fine sand and water on the lower one, so that the opposed surfaces mutually grind one another, and when this process is completed on one side, they are reversed, and the same operation is performed on the other side. The plates have now the appearance of ground glass, and the surfaces are further ground by fine emery powder, which causes them to be much smoother and more ready for the final polishing. Formerly this was entirely done by hand, women generally being the operators, and oxide of iron, called crocus, mixed with water, the material employed for polishing. Now, however, a more rapid and perfect method is adopted by the use of machinery. A table is prepared which moves from side to side, giving to the plate a lateral motion; and above is a beam, in which holes are drilled at intervals, through which short iron rods, nearly an inch in diameter, pass. On these are padded iron buffers, covered on their under surface with leather; while, pressing down these rods, and therefore the buffers, are springs, which act with considerable force, but which are able to yield to pressure caused by any inequality over which the buffers may pass. The glass plate is fixed upon this table, and its upper surface is exposed to the action of the buffers, while oxide of iron, in a very fine state of division and mixed with water, is allowed to come upon its surface. The glass travelling from side to side is rubbed by the buffers in a lateral direction, and has also a longitudinal motion, so that every portion of it is rubbed equally. If any inequalities occur on the glass, the springs which press down the buffers give way and allow them to rise over it, and this process is continued for some time, until at last the plate receives the polish so characteristic of plate glass. It is then removed from the table and examined by skilled persons, and whatever defects can be removed by hand, are remedied.
Another kind of plate glass, called "patent rolled plate," is made by ladling out from a pot molten glass in the proper state of consistence. The ladle is brought over a small glass table, and a similar operation is performed to that already described. This patent rolled plate is sometimes made with grooves on one of its surfaces, or with patterns in imitation of diamond quarry glazing, and, in fact, with any designs, according to the taste of the manufacturer. These designs are all engraved upon the table, and communicate their patterns to the soft glass; but the smooth surface of such glass which comes in contact with the roller is slightly undulating, though polished. This method of glass making was invented and patented by Mr. Hartley, the noted manufacturer, of Sunderland.
A lighter kind of plate glass, which is principally used for glazing the better class of pictures and engravings, and called "patent" plate, is simply sheet glass polished after the manner of plate glass. Crown glass, which only admits of being cut into small squares, is also used for picture glazing, but is more carefully prepared, and is called by the name of "flatted crown."
Looking Glasses.—Plate glass is employed for making looking glasses, and two processes are now in use for silvering them, the first of which consists in applying a sheet of tinfoil saturated with quicksilver to one side of the glass. The operation is conducted as follows: on a perfectly smooth table a sheet of stout tinfoil is laid, and on it is poured quicksilver, which is distributed evenly over the surface with a hare's foot. When the whole sheet is amalgamated with the quicksilver, more of that substance is poured over it, until it flows quite freely. The glass plate to be silvered, having been made perfectly clean, is floated upon the surface of the quicksilver, an operation requiring care, and is then covered all over with weights, by which means the excess of quicksilver is pressed out, and the glass comes in contact with the amalgamated sheet of tinfoil, to which it adheres entirely. This ancient method of silvering glass has some advantages over the one next to be described. The colour of the plate is, according to artistic taste, better, and with care the plate will not lose its brilliancy for years. I have in my possession some old glasses, the silvering of which is very beautiful, except where it has suffered from mechanical injuries. Silver can be precipitated from a solution of nitrate of silver in several ways, and in some of these specimens was like a bright film. If a crystal of nitrate of silver be put into a test-tube with some bitartrate of lime, and the mixture be rendered ammoniacal and gently warmed (it being kept in motion during the experiment), its sides will be covered with a very brilliant deposit of metallic silver. Oil of cloves and grape sugar have also the power of reducing metallic silver from ammoniacal solutions of the nitrate, when gently warmed; but the mixtures must not be made too hot. In silvering plates of glass, they are first well cleaned, then placed in a perfectly level position, and the silvering liquid is poured over the surface, the room in which the operation is performed being kept sufficiently warm to assist the deposition. When enough silver has been deposited on the glass, the liquid is poured off and the plate dried, while the silver film is protected by being coated with a suitable hard varnish. The composition of the mixtures used by different persons is generally kept secret, though the chemical principle of the reduction of the silver salt is the same. Glasses silvered by this process sometimes lose their brilliancy, by becoming covered on their silvered side with small spots. It is however stated that this results either from a bad system of deposition, or from the film of silver not being sufficiently thick and solid.
Flint Glass, although called by this name, is not made from flint, but from the best sand, of pure and dazzling whiteness, obtained from Alum Bay, in the Isle of Wight, and from Fontainebleau, in France. The cost per ton is from 1l. to 1l. 15s., whereas the price of the sand used for making plate glass is about one-eighth of that amount. The alkali employed is generally extremely good carbonate of potash, whereas soda is used in the manufacture of the other kinds of glass which have been described. The addition of a small quantity of black oxide of manganese is sometimes necessary to correct the slight tint imparted by iron, which seems to be always present in minute quantities, even in the purest samples of sand. Oxide of lead in the form of red lead, in this sort of glass, takes the place of lime. The advantages derived from using the oxide are, that it makes the mixture more fusible, and also imparts that particular brilliancy and lustre so peculiarly characteristic of well-made flint glass. In different works, various mixtures are made for the composition of the glass; but to give an idea of the proportions in which the materials are mixed, it will be well to quote the statement of M. Payen, who says that of the finest crystal flint glass, the following is the composition: sand, 3; red lead 2 to 2¼; carbonate of potash, 1½ to 1-2/3. A little nitre or saltpetre is used as an oxidizing agent. The glass-pots employed in this branch of the manufacture are covered, so that the flames of the furnace do not come in contact with the materials, the object in thus isolating them from direct contact with the flame being to prevent the entrance of impurities, by which the colour might be injured. On account of the pots being covered, the materials take a much longer time to get hot, and require quite double the time in founding that sheet or plate glass does; the presence of oxide of lead materially assisting the rapidity of the fusion. When flint glass is ready for working, the time required to work off a pot of it is much longer than that which is required for a pot of crown or sheet; and it is a matter of considerable importance, that the furnace-man should so manage his fires as to keep the glass in a proper working condition, that is, he should not let it get too cold (therefore too solid) nor too fluid. Flint glass is worked off by the blower into wine-glasses, tumblers, decanters, and other suitable vessels. Let us take a wine-glass as an illustration of the method of working. A small quantity of glass is gathered on the blowpipe, which is much smaller than that used in making sheet, and is blown into a bulb, which may be slightly elongated or globular, the forms being given to it by the motion which the workman imparts to his blowpipe while he is blowing, or after he has blown, into the mass. In the case of a wine-glass, an assistant boy gathers a small quantity of glass on the end of a small pointel, or solid iron rod. This is placed on the side of the globe opposite that which is in connection with the blowpipe, which is then detached by touching the glass nearest it with a piece of iron, wetted with cold water: this causes a crack, and a gentle tap causes separation. The workman then moulds the opening made by detaching the blowpipe, in order to do which, he has to apply the glass often to the mouth of the furnace, to soften it. He then opens out the globe into the shape of a cup with a pair of small iron tongs, with legs uniform in shape, slightly tapering and smooth, and he uses a peculiar kind of scissors for trimming the edges. The other parts of the glass are moulded with the tongs, accuracy of size being obtained by means of measuring compasses and a scale. The workman sits during this operation in a seat with arms, laying the pontee on them, and turning it, so as to make it move backwards and forwards with his left hand, while with the tongs in his right he gives the glass the desired form.
Before passing on to a description of the manufacture and composition of coloured glasses, it is necessary that I should make a few remarks on the difficulties under which our English glass makers labour, owing to not paying sufficient attention to the scientific treatment of their mixtures. It has already been stated that glass is composed of a mixture of silicates, which are definite chemical compounds. Some are much more dense than others, and are therefore liable to sink, so that the glass taken from one part of the pot will be very different in composition from that taken from another part; besides this, it is found on examination, that other portions of the materials employed are present in such proportions, that they cannot possibly exist in the form of true silicates. M. Dumas, the distinguished French chemist, asserts, and with truth, that glass ought to be a true chemical compound. This, however, does not seem to be the opinion here; and sufficient attention is not paid by English manufacturers to mixing their materials, so as to form definite silicates, the result being that glass is produced with a striated effect. This is easy to be seen in the common kinds, as in bottle glass; but owing to the more careful and prolonged fusion of the finer varieties, such as plate glass, this defect is to a considerable extent remedied, though not altogether overcome. In the French manufacture of plate glass, more attention has been paid to the chemical composition of the various silicates which enter into it. At St. Gobain, a plate glass, is produced which, on analysis, is found to contain definite silicates, and without any excess of material which does not enter into chemical combination; and the consequence is, that this glass is more perfect and homogeneous than that made in this country. No doubt this superior quality is owing to the fact, that the famous chemist, Gay-Lussac, devoted much of his time to assisting in the manufacture carried on at these works. We cannot over-estimate the importance of a scientific superintendence, not only of glass-works, but of all other manufactures in which chemical reactions take place; for although experience may lead a cautious observer to produce substances of nearly correct composition, yet the assistance of a scientific observer is of the greatest importance, because, what under other circumstances must be simply empirical, is under his guidance carried on according to definite and fixed laws.
Mention has already been made of how, in the case of mixing carbonates of soda and potash, the one assists the fusibility of the other, and this is more particularly true in the mixture of silicates in the composition of the ordinary glass. Silicates of soda and potash are separately much more infusible than a mixture of the two, and the addition of other silicates to them renders them more fusible still; silicate of lead, as has already been mentioned, causing the glass into whose composition it enters to fuse at a much lower temperature than it would do if that silicate were absent. Again, if the silicate of lead be present in too large proportions, and if great care be not taken in the manufacture of lead glass, the silicate of lead, from its greater density, will sink lower among the molten silicates, and will therefore cause a larger proportion of lead to be in the glass at the bottom of the pot than there is at the top. We often notice in tumblers and decanters of the cheaper kind, that there are very distinct striæ running through the whole substance in some particular portion of the glass. Now this is owing to the greater density of the lead silicate, which sinks lower down in the collected mass of glass, and therefore imparts to it this peculiar effect. When a pot of flint glass is worked off, that which remains at the bottom usually contains more lead than that which is worked off in the earlier part of the day.
Coloured Glasses.—It has been before shown that silica unites with metallic oxides; in fact, glass is nothing but a compound brought about by the union. With certain metallic oxides, silica forms coloured silicates or glasses; and these, when fused with colourless glasses, impart to them the colour of the silicate. Oxide of iron colours glass either green or yellow, according to the nature of the oxide; the silicate of the protoxide of iron being green, and that of the peroxide, yellow of a slightly brownish tint. Copper forms two oxides, the suboxide and the protoxide; the suboxide colours glass red, while the protoxide renders it green. Black oxide of manganese colours glass purple; but if large quantities be used, it makes it perfectly black. Sesquioxide of chromium imparts a beautiful green colour to glass, while oxide of uranium produces an opalescent effect of yellow with a tinge of green. This latter, by the way, has the power of reducing the ultra-violet rays of the spectrum to luminous rays, and, when held in the rays of a spectrum obtained by the electric light, produces an extremely beautiful effect, which is called fluorescence. A small quantity of the oxide of gold tints glass pink, but the colour becomes extremely rich and ruby-like, when a larger quantity of the oxide is employed. Oxide of cobalt in very small quantities yields, with silicic acid, an intensely blue silicate. This substance, carefully prepared in a special manner and ground to a fine powder, forms the well known water-colour pigment called smalt. Oxide of silver stains glass from a delicate lemon tint to a deep orange, in proportion to the quantity of the oxide employed.
With the exception of the last-named colouring material, the above mentioned are mixed together with the substances which form the glass, and are melted in the usual way in glass-pots, except that they are treated with considerably more care, in order that their tints may be true. Oxide of silver, however, is never mixed with the materials of which the glass is made, but is applied to the surface in the following manner: a solution of nitrate of silver mixed with some substance, such, for instance, as chalk, may be painted upon the parts of the glass which it is desired to stain, and these are heated to a dull red heat, in what is called a "muffle." Wherever the oxide of silver, which is reduced from the nitrate by heat, comes in contact with the glass, the latter is stained more or less intensely, according to the quantity of silver present. Pure metallic silver may be melted with metallic antimony, and the mass ground to a fine powder in water. This powder, after being mixed with some Venetian red and gum water, is applied to the surface of the glass, which is, when dry, heated to a dull red heat in a muffle, producing the yellow stain, which can be seen after the Venetian red and the excess of silver have been scraped off. The reason why silver, or oxide of silver, is not mixed with the glass materials and fused with them, is because it does not readily unite with oxygen, and, when it has done so, it loses its oxygen again at a high temperature, and becomes reduced to the metallic state; and inasmuch as metals have no effect whatever in staining silicates, glass made in this way would not have the yellow colour which it has, when the silver is heated upon its surface to a much lower temperature in a muffle; for the temperature to which the constituents of the glass must be heated, so as to cause them to burn it in, would be so high, that the oxide of silver first formed at a lower temperature would be reduced to the reguline or metallic state. Gold also, like silver, does not unite with oxygen readily, or remain in union with it at high temperature; therefore great care is required in the preparation of glass to be coloured by oxide of gold; the form in which it is used being generally that of the purple of Cassius, made by precipitating a salt of tin with a salt of gold. This substance is mixed with the glass to be coloured, and heated in a suitable glass-pot. Portions of it are gathered and allowed to cool, these being generally of a yellowish, brownish, and sometimes reddish tint, though they have not in any case the same beautiful red colour which they produce when applied, as will be immediately described, to the surface of white glass. A certain quantity of white glass is gathered from the glass-pot in the soft state with one of these pieces of gold glass; the whole mass is heated until both become soft, and is then blown and formed into sheet, which, on examination, will be found to consist mainly of white glass, with its surface thinly covered with the glass stained with oxide of gold, while the beautiful ruby colour, which the gold imparts to the glass, appears pure and distinct. If such glass as this be heated to too high a temperature, as when it is used in the manufacture of stained glass windows, the ruby colour is in part, and sometimes altogether, destroyed, for the oxide of gold loses its oxygen, and metallic gold is left behind, which does not yield a colour to the silicate. I have in my possession a piece of French glass of a pale sapphire tint, which, when heated in the oxidizing flame of the blowpipe, assumes a brilliant and intense ruby colour, showing that in the first condition, the gold is not in a state of oxidation sufficient to impart colour to the glass.
When the suboxide of copper is mixed and fused with the glass which it is intended to colour, the result is an opaque substance, almost like red bottle-sealing-wax, which is treated in a manner exactly similar to the gold glass; viz. it is coated with white glass, and blown and shaped into sheets, which owe their intense ruby colour to a thin film of the coloured glass closely adhering to the mass of the white upon which it is placed. Glass made in this way is called "coated," and sometimes "flashed" glass, and is extremely useful for ornamental purposes, for by the action upon the coloured surface of hydrofluoric acid, the ruby coating can be eaten away, and the white glass beneath left entire. If the backgrounds of the patterns be painted upon the ruby side with a material like Brunswick black, which is able to resist the action of hydrofluoric acid, and if the plate of glass, on its ruby side, be exposed to the action of the vapour of this acid, or to the action of the acid in solution in water, in a short space of time the pattern will be eaten away; and if the Brunswick black coating be removed with turpentine, a sheet of ruby glass will be obtained with a white pattern etched upon it.
Owing to the powerful colouring properties which oxide of cobalt exerts, a very deep-coloured blue glass can be made, which can be treated like the red copper glass, and may be made to coat and cover in the same way the surface of plates of white glass. Purple glass, coloured with oxide of manganese, and green glass are also sometimes used as coating materials for white glass, but other colours are never employed in this way.
It is manifest that if different metallic oxides be used with the same glass, mixed tints will be produced, so that by mingling small quantities of oxide of cobalt and protoxide of copper, a blue glass having a greenish hue may be obtained. The revival of glass painting has caused manufacturers to turn their attention to these mixtures, in order to produce tints resembling those of ancient stained glass. Messrs. Powell and Son, of Whitefriars, were the first to perform experiments on these mixtures, and after much laborious attention and patience their efforts have been crowned with great success, for they have been enabled to produce glass as beautiful in tint and in texture as the best specimens of ancient manufacture. Their example has been followed by others, such as Messrs. Hartley of Sunderland, and Messrs. Chance and Co. of Birmingham.
While treating of the effect produced by different metallic oxides upon colour, it may be well to mention that the opaque glasses used for such purposes, as the enamelling of watch-faces, are made by mixing with the materials a certain quantity of arsenious acid (or white arsenic), in much larger quantities than when it is employed simply to correct the tint imparted to glass by the iron impurities in the sand. Oxide of tin also renders glass white and opaque, and a certain quantity of bone ash will produce a similar effect, though not in so satisfactory a manner.
Glass painting first became general in this country at the time when the Early English style of architecture prevailed, and some of the best specimens were executed during that period. By the best specimens is not meant, that the figures painted upon those windows were artistically as correct as similar works of a later date, but that they were designed and executed in accordance with those principles, which should always govern the adaptation of a substance like glass to ornamental purposes. The earlier mediæval artists depended for effect more upon the boldness of their outline, than upon the intensity of their shading or the delicacy of their manipulation. The form of a thirteenth-century figure is merely indicated by a few bold and well drawn outlines, the features being formed by lines, the pupils of the eyes by simple well-shaped masses of opaque pigment; and such a treatment as this was quite sufficient to convey what was, to the observer, more or less a symbolical, than a truthful representation of the Scripture history which they were intended to illustrate. These artists remembered that windows are openings in a building, through which light has to pass, and they did not, therefore, like many of the later imitators, render them opaque by masses of intense shadow, which perfectly obscure the colour of the glass upon which the picture is painted, and render the passage of light through it simply impossible. The thirteenth-century glass painters, too, in the treatment of their shadows, bore this great principle in mind, and instead of daubing and stippling them on, usually indicated them with a thin wash of enamel colour, intensified in parts by lines crossing one another, and therefore called cross-hatching, through the interstices of which the light, although subdued, was able, in a measure, to pass.
But as the object of this article is not to discuss the merits of the various styles of glass painting, however much I might desire to enlarge upon it, I pass on to a description of the methods employed in the manufacture of stained glass windows. In the first place, after a design has been drawn, in which the effect of the window as a whole can be carefully considered, cartoons of the figures and ornament are made of the exact size of the intended painting. And here it should be noted, that all the lines should be extremely clear, precise, and well drawn, because it is from these that the workman, who is not usually himself an artist, has to convey on the glass the feeling of the artist. The cartoon, when completed, is laid down in pieces for convenience-sake on a table, and fastened with small nails. The glass-cutter then selects the various coloured glasses which are required to be inserted in their proper places, so as to carry out the design of the artist. For instance, a piece of white or yellow-tinted glass is cut to the shape of the face. If the figure be a small one, the hair also is included in this; and probably in the figure of a saint, the nimbus which surrounds the head may be included; while in larger figures, particularly in the earliest styles, the face was of glass of one tint, the hair of another, and the nimbus of one or more tints, different from either of these. Sometimes, in the later styles, the hair, after the face was painted and burnt in, was stained with the silver stain already described, so that when the glass was cleaned, it was of a yellow colour. However, not to enlarge more upon these points, which really belong more to the artistic than to the industrial part of window painting, let us proceed to the consideration of manipulative details. The outlines of the figures and ornament are painted with a substance called "tracing brown," made by mixing with a flux some oxide of iron, heating them together in a crucible and grinding the product to a fine powder, which is mixed with certain vehicles adapted to the particular use to which it is to be applied. Different fluxes are employed by different glass painters; some contain borax, because such fluxes fuse more easily, and therefore cause the glass which is painted to be exposed for a less time, and to a lower temperature, than when less fusible fluxes are used.
It is always satisfactory to an author, to feel that his articles have been of some use to those whom he hoped to benefit. Since this article was written a letter appeared in one of the architectural journals, complaining that the glass furnished by manufacturers to glass painters was of inferior composition to that which was used by the manufacturers of ancient stained glass windows. In fact, it was asserted that modern glass was not made with due care, and that to this was owing the unfortunate disappearance of some of the painting and tracing of modern stained glass windows; but that this is not the case, is manifest to all who understand the manufacture of glass. The real reason why the colouring matter with which glass painters outline and shade their designs, has in many instances gradually come off from the surface of the glass, is, because the fluxes used for making it adhere to the glass are of such a composition, that they themselves have by the action of time become disintegrated.
Some time ago, a person engaged in the manufacture of the enamel plates used for railway lamps, on which are written the names of the stations, called upon me, and told me, that the enamel which he employed had become dark, spotty, and in many cases had peeled off from the glass. The reason of this is identical with that which occurs in stained glass windows, viz. that the fluxes that he used were not suitable for the purpose, considering that they had to withstand the action of the weather. From an analysis made of these fluxes (not of those last alluded to, but of those which have been employed in stained glass windows), it appears that large quantities of borax have been introduced; and, wherever this is the case, no reliance whatever can be placed on the permanency of pictures painted with such fluxes. I have appended a few receipts for fluxes, which can be used with safety by any glass painter who will take the trouble to try them. But I must strongly advise that all those who are connected with the making of fluxes in any glass painting establishment, should master sufficient chemical knowledge to enable them to ascertain the behaviour of the materials, with respect to one another, as well as of the nature of the glass upon which they are employed; for very much indeed depends upon a correct knowledge of the character of the glass as to whether it be hard or soft, what it contains, and of the temperature at which the glass becomes sufficiently soft to form a firm and enduring union with the colours fluxed upon it.
Receipts for Fluxes.
|Flint glass (powdered)||10||parts.||}||moderately
|Flint glass (powdered)||3||"||}|
|(Mixed with four parts of the first flux, soft.)|
The use of very soft fluxes is attended with this inconvenience, that the boracic acid contained in them is generally acted upon by moisture and becomes hydrated, and in this condition often causes the painting to peel away. Harder fluxes, although they have the disadvantage of necessitating the glass to be submitted to a much higher temperature for a longer time in the kiln or muffle, are the best, and, with judicious management, can be used without any injurious consequences to the work on which they are employed. Lead fluxes, containing oxide of lead, are sufficiently fusible for all ordinary purposes, and are not liable to the same objection as fluxes containing borax. Suppose, then, it is desired to paint the outlines of a face, the glass is cut to the shape of the face in the cartoon; it is then laid upon it, and the painter, seeing the lines through the glass, is able to trace them with his brown paint upon its surface. He generally uses gum water as his vehicle, and puts on the shading also with the same mixture, though sometimes it is found necessary to use a substance which is not affected by moisture, as for instance, tar-oil. It is impossible, in the short space of this article, to indicate those occasions on which one should be used in place of the other; a knowledge of this can only be obtained by consulting authorities in which details are more minutely given, or by watching the operations of the glass painter in his workshop. When the face is finished, it is removed, and another portion of the figure, say a piece of the drapery, is proceeded with in exactly the same way; and so, by a repetition of this process in all parts of the figure, it is completed, and looks very much like a puzzle, the parts being put together on the cartoon before the work is finished, in order to see that the whole is harmoniously treated. In shading the face, hands, and those parts of the drapery which require it, a glass easel is used, on which the figure is put together, and the parts made to adhere by wax, so that the artist is able, while painting, to form an idea by transmitted light of the effect which will be produced when the window is finished. The ornament is painted in a similar manner, but usually not with the same care in the details of its execution.
When all the glass is painted, it is fired in a muffle, upon the proper construction of which a great deal depends. It is usually made of iron, and should not be more than 15 inches from its bottom to the top, though its width may vary. It is never well to have muffles for firing glass for painted windows larger than about 2 feet wide, by 2 feet 6 inches deep. The top of the muffle is usually slightly arched from side to side, and it is placed in the furnace on a tolerably thick stone floor, so that the bottom may not get too hot. The fire, which is lighted below, is allowed to play up its sides and over its top, the flue being so built as to draw the flames in that direction, for a top heat is the best heat for firing glass regularly. The muffle is arranged with ridges in its sides, passing from front to back parallel to one another on one side, and exactly opposite to corresponding ridges parallel to one another on the opposite side. These metal ridges are intended to receive iron plates, and there is generally about an inch or rather less between the top of one plate and the bottom of another, when the muffle is perfectly filled. The plates are covered over with perfectly dry powdered chalk or whiting, and the pieces of glass are laid upon them with their painted sides uppermost. When the plates are charged, they are put into a muffle with an iron door, in the centre of which is a hole, and a conical tube with the base attached round it. It is larger than the opening at the other end, which projects some 6 or 7 inches from the surface of the muffle-door at right angles to it. A second door is then placed at a short distance from the first, the tube passing through a hole made for the purpose in it. The orifice is usually stopped by a piece of fire-clay, which can be removed at pleasure. The use of the tube is, to enable the manager of the kiln to look into the muffle, from time to time, to see that the glass does not get too much heated. When the firing is completed, the fire is raked out and the muffle is allowed to cool very slowly, and by this process the glass becomes annealed.
When it is desired to apply to any portion of white glass some yellow silver stain, this can be done either in the first firing, by floating it on to the places to be stained, and allowing it to run in a sort of stream from the brush, so that it will evenly cover the surface and cause the heavier portions of the stain, namely, the mixed metallic silver and antimony, to sink regularly to the bottom, and come fairly in contact with the glass. Not very long ago, it was mentioned to me by a glass painter of note, that the workmen much prefer using the old stain made with silver and antimony, to that which is produced by using nitrate of silver. This really is a mistake on their part, for, when properly managed (and the knowledge of how to manage this stain can be acquired with very little trouble), the nitrate of silver stain is by far the best, and produces much better tints, with less chance of what the men call sulphuring when the glass is fired. This sulphuring is simply the result of opacity, obtained by heating the glass to too high a temperature. If the staining is to be performed in the same firing as that by which the painting is to be fixed, it is quite clear that the outlines of the part to be stained must be painted in, with tar-oil, or with some such substance which is not affected by the moisture of the stain. However, in general, the staining operation is performed after the first firing, that is to say, those pieces of glass to which the silver is to be applied are stained in the method above described after the first firing, and are then fired again, because the heat required to produce a good stain from silver is of a somewhat different character from that which is required simply to fuse the flux that binds the pigment to the glass. A longer and less intense heat, technically called a "soaking," is the best for producing an even and pure yellow tint. If the temperature be allowed to rise too high, the oxide of silver, which alone can stain the glass, gets reduced wholly or in part, and when this happens to only a slight extent, it destroys the transparency of the stain; and when it happens to a great extent, it destroys its colour altogether, making the glass opaque.
It is a matter of astonishment to me that glass painters do not use a ruby stain, which, with a little practice, can be managed quite as successfully as the yellow silver one. It is true that it would be impossible to fire the ruby and the silver stains together, and it would not be at all convenient to fire the ruby stain at the first firing of the painted glass. The method of staining ruby is as follows: grind up carefully some black oxide of copper, mix it with water (or with a small quantity of gum added), float it on the parts to be coloured, place it in a kiln and heat it. Black oxide of copper, when mixed with glass and melted in a glass-pot, makes the glass green; suboxide of copper, which contains less oxygen than the black oxide, when treated in the same way, makes it red. Now, if it can be reduced to the lower oxide of copper, while the black oxide of copper on the surface of the glass is heated, it will then colour the glass red. The best way of reducing the black oxide, is to connect the muffle with a gas-supply pipe, and allow coal gas to pass during the whole time that the heating process goes on. The action of the gas, which contains hydrogen and carbon, is to take away oxygen from the black oxide of copper, when it is at a high temperature; and, as soon as sufficient is taken away by the hydrogen to reduce the black oxide to the state of suboxide, it stains the glass red. It does not matter if the reducing action be continued longer, so that the oxide of copper be reduced to the metallic state; for at that temperature, the stain produced by the red oxide of copper is not removed by the continued action of hydrogen gas. The employment of this process would certainly enable artists who paint in the later styles of glass painting, to very much enrich their draperies, and to produce, more easily, effects which now can only be obtained by a complicated system of lead-work.
When the pieces of glass which have been fired are perfectly cold, the next process is to unite them altogether by peculiarly shaped strips of lead, which are of various kinds, according to the character of the subject required. The lead has a thick part or core, and at right angles to the top and bottom of this are thin plates called the "leaves." The core is milled with little ridges running at right angles to them, so as to enable the workman to bend the lead about with facility. The edges of the piece of glass to be leaded are placed between the leaves and resting upon the core, and the lead is thus arranged all round the glass, and is then laid in its proper situation upon another cartoon, prepared from the one from which the figure was painted, and indicating simply, by lines, where the lead-work is to come. The first piece is fixed by means of nails temporarily placed through the lead. Those pieces which touch it in the design are put in their proper positions, so that the edge touching the next piece will be underneath the opposite leaves to those which confine the first. This operation is repeated, till all the parts of the design are surrounded by lead, and by it united to one another; the joints being secured by solder, generally applied by gas. Nothing now remains but to fill in the interstices between the lead and the glass, so as to make the window firm, solid, and water-tight; and this is done by rubbing into them with a scrubbing brush a cement, usually made of white lead, oil, and plaster of Paris. This composition varies in different stained glass works, nor is it material, provided that the substance hardens, does not crack, and is waterproof.
From this description it will be seen, that the various colours in the different parts of the window are put in as pieces, and that no colours, properly so called, are applied by the brush to the surface. There are, however, certain tints of the "tracing brown," which can be obtained by the addition of black oxide of manganese, or by a different method of preparation of the oxide of iron, to give it its body. Sulphate of iron, when heated, loses its sulphuric acid, and the oxide, which was, as sulphate, in the state of protoxide, becomes, by heating, the red or peroxide of iron; its tint, when made in this way, being generally lighter than the tint of that form of oxide which is employed as ordinary tracing brown. It is sometimes called flesh tint, though this is decidedly an objectionable name for it.
It has been suggested to me, that I should give some receipts for the manufacture of the enamel colours used in mediæval glass painting; I have therefore added a few which are easily prepared. Others of a more complicated nature had much better be obtained from the makers of the enamel used in porcelain painting. And here again, let me remark, that in ordering fluxes from these manufacturers, it should be stated especially that a flux is required which does not contain borax, nor should the painters in any establishment be allowed to use these softer fluxes, which they are almost certain to do, unless forbidden; for though they are easier to work with, they will infallibly lead to calamitous results.
|Oxide of tin||2||parts.|
|Oxide of antimony||2||"|
|Oxide of antimony||4||"|
|Persulphate of iron||1||"|
|Black oxide of manganese||2·25||"|
|Flint slate (powdered)||4·0||"|
|Crocus (oxide of iron)||3||"|
|Green sulphate of iron (calcined) mixed with six parts of these No. 2.||1||"|
|Light Red for Flesh Tints.|
|Carbonate of lead||1·5||"|
|Persulphate of iron (calcined)||1||"|
The use of enamels—that is, substances which impart various colours to the glass, when placed on its surface by their fusion—is not admissible in windows which pretend to belong to any of the earlier styles of glass painting; though enamel painting is used for the decoration of houses, and sometimes, as I consider very improperly, for the decoration of church windows. One sheet of glass, colourless and transparent, or it may have its surface ground, is usually employed. A subject is painted on it with enamel colours, much as subjects are painted upon porcelain. When the work is completed, the glass plate is fired, and thus the colours become semi-transparent, and perfectly adherent to the plate; but they are not clear and bright, and transparent, as are the colours of glass which is coloured in the pot, and therefore have not the same brilliancy, nor do they allow of the same bold and effective treatment.
It is much to be desired that amateurs who can draw, and who have a feeling for this particular style of art, should devote a portion of their time to its execution. They will find it to be extremely agreeable and pleasant, and the few difficulties which they meet with in their first attempts will be readily overcome by perseverance, or by applying for assistance and advice to gentlemen engaged in the pursuit of this interesting profession.
Moulded and Cut Glass.—Flint glass is now very commonly blown in moulds, and this art has been brought to such perfection that moulded decanters and tumblers have an appearance very similar to that of cut glass. The moulds are always made of metal, and so constructed, that they open out into two or more pieces, which are generally hinged to the bottom of the mould. The workman places it on the ground, and fixes it by standing on projections from its side. He then gathers a suitable quantity of glass on the end of his blowpipe, which he places in the mould, and the side of the glass touching it will thus have impressed upon it whatever form is engraved on it. After the glass has become hard, the mould is opened, and the glass vessel is removed and annealed.
When it is desired to cut a design on the outside of a tumbler or wine-glass, the vessel is, in the first instance, blown of a thicker substance than if it is to be left uncut. The necessary shapes, which are usually in facets, are cut upon it by the action of sand and water, a lathe of a very simple construction being used to give a rotary motion to cutting discs, made of stone and kept continually moist by water dripping on them, so that when the glass is pressed against them, the required portion of its surface is worn away. The usual diameter of these stones is about 10 inches. After the rougher stone has been used, a finer kind of sandstone disc is employed, or a disc of slate, upon which sand and water are allowed to drop, and the already roughly cut surface is, by their action, partly polished. Copper discs with flattened circumference are used for polishing the glass, and for this purpose, emery mixed with oil, is applied to the edges of their circumference.
Ground Glass is made by rubbing the surface of glass with sand and water, just as in the first operation of plate glass polishing. But a very ingenious method is now generally adopted for grinding glass, by placing it in a cradle, so that it can swing from side to side; sand and water are placed upon the glass, and it grinds itself, so to speak, by this operation.
Annealing and Devitrification.—As the word "annealing" has been often used in this article, it will be well to explain what is its action. If a piece of molten glass be dropped into water, it will assume an oblong shape, the lower end of which will be round, while the other will taper off into a fine point. These drops, which have received the name of Prince Rupert's drops, look like pieces of ordinary glass, and if the small end of one of them be broken off, a sort of explosion takes place, and the whole mass flies into a thousand minute pieces, some of which will be found to have been driven to a considerable distance. Here then it appears, that when the skin, which is perfect and entire in the Rupert drop, is broken, the bond which held together the constituent particles is broken also, and so they are acted on by a repellent force, and fly away from one another. If hot water be poured into a thick common tumbler, it very generally cracks it: but if the tumbler be thin and of better manufacture, it will bear almost boiling water without cracking. In the first case it has been badly annealed; and besides this, glass being a bad conductor of heat, from its thickness, the heat imparted by the hot water expands the inner surface, while the outer coating, not being warmed, does not expand, and, retaining its original form, is burst. If, however, a tumbler be thick and properly annealed, there is not so much danger of its breaking, when a portion of it is exposed to a considerable rise of temperature. In the case of the Rupert drops, they are not annealed at all, and so there is no cohesive bond between the particles, such as there would be if they were properly annealed, that is, if, instead of being cooled suddenly from the molten state, they were allowed to cool in a heated chamber very slowly. After glass has been heated, the particles of which it is composed take a long time to rearrange themselves, so that in the manufacture of thermometers, it is necessary, after sealing up the bulb and tube which contain the mercury, to allow them to remain for a long time; otherwise the pressure of the air on the outside of the bulb, not being supported by any air on the inside, causes the particles of glass to become more compact, and thus renders the capacity of the thermometer bulb and tube smaller than it was, when the thermometer was first sealed. It seems that the process of annealing glass gives time for the particles to arrange themselves in such a way, that when the glass is cold, it will not be so liable to fracture from sudden changes of temperature.
Considerable curiosity has been excited of late by a new invention, which has resulted from the investigations of a Frenchman. We have been told that tumblers and wine-glasses, and other glass utensils, could be so treated that they would never break; and experiments performed upon many samples of these glasses led one to suppose, that the object had been attained. There is no doubt whatever, that some who have had experience of what is termed toughened glass know, that in many cases very uncertain results are obtained in the resisting power of the glass to the action of a violent blow. Before, however, entering into some researches which I have made on the subject, it will be well to state what is the nature of the change which the toughening process produces in the glass, and this seems to be a fit place for this consideration, as the method of making, and the behaviour, of Prince Rupert's drops, have just been discussed.
The physical properties of these Rupert's drops have been examined with great care by M. Victor de Luynes, and the results of his experiments have been communicated to the Société de Secours des Amis des Sciences. For the purposes of this article, many of his experiments have been repeated, confirming in general his observations, and others have also been instituted. The toughness and hardness of these drops are remarkable; the thick pear-shaped portion will bear a sharp stroke with a hammer without breaking; nor can it be scratched with a diamond. To break the tapering thread or tail, as it may be conveniently called, requires considerable force. To find out what weight was required to do this, a series of experiments was performed, the results of which are given in the table following. The tail of a drop was placed over a small hole bored in the top of a table; a hook was then adjusted round a part of the tail which measured 19 on a Birmingham wire gauge; below the table and attached to this hook, a scale-pan was hung. This pan was then carefully loaded, all shock being avoided, until the thread was ruptured and the weight required to effect this was then noted:
|White Glass Rupert's Drops.|
It will be observed that the drops made from green bottle glass withstood a greater strain than those made from crown glass; the latter, in fact, did not break throughout their mass, but left a portion of the bulb unbroken, showing some fault in the tempering. It was with difficulty that the workmen could be induced to make drops out of this kind of glass, as they knew by experience that they usually failed to break perfectly, and they stated that it was quite impossible to make them with lead glass. To ascertain what force was required to fracture a thread of like dimensions that had not been tempered, one of the drops was heated to redness, and annealed by allowing it to cool very gradually. When subjected to the same trial, it was fractured by a weight of 12 ozs., and the drop did not break into small fragments, but behaved exactly like ordinary glass, thus showing that the glass had been untempered by the heating process. A piece of glass rod, drawn out into a thread in a gas flame, when subjected to the same conditions, bore a strain of 10 oz. A sewing-needle of the same thickness was broken by a weight of 3 lb. 14 oz., thus showing that the tail of the Rupert's drop was very much manner as to allow the tail to dip into hydrofluoric acid, it is found, that when the surface or skin is eaten away to a certain depth, broken. In whatever way fractured, the particles, when examined by the microscope, show a crystalline structure, and do not at all resemble pieces of ordinary glass; when rubbed between the palms of the hands, they do not cut, nor scratch, nor penetrate the cuticle. If a drop be enclosed in plaster of Paris so as to leave a portion of the tail exposed, it may then be broken and all the particles will remain in situ. On removing the plaster, it will be found that the drop has been broken up into thousands of minute needle-shaped particles arranged in cones, the apices being in the direction of the tail. It would appear then from these experiments, and from observations with polarized light, that the glass in the interior of a Rupert's drop exists under enormous tension, and that it is only prevented from bursting into fragments by the outer skin; on its being broken in any part, the bond which holds together the constituent particles is broken also, and so, being acted upon by a repellent force, they fly away from one another. There is another kind of toy resembling in some respects the Rupert's drop, known as the Bologna bottle or philosopher's flask. It has the form of a soda-water bottle with the neck cut off, the bottom being rounded off and very much thicker than the walls. These flasks are sometimes formed accidentally in glass-works by the workman, who, in order to examine the quality of the glass, takes out a portion from the pot on the end of his blowpipe, and blows a small quantity of air into the mass, manipulating it in the usual manner. Whilst still at a very high temperature, it is detached from the blowpipe, and is probably allowed to fall on the ground in a place where there is a current of cold air, the exterior thus becoming suddenly chilled. When cold, these flasks will bear very rough handling, and will withstand the blow of a hammer on the outside, it being almost impossible to break them by striking the bottom; the interior will also bear the blow of a leaden bullet falling into it from a considerable height, but if a few grains of sand be allowed to fall into it, or if the inside skin be slightly scratched, the mass splits into fragments in the same manner as a Rupert's drop. The examination of these curious phenomena leads us to the subject of "toughened glass," as it has been termed. The invention of rendering articles of glass less fragile, which has given rise to so much public attention during the last year, is due to M. Alfred de la Bastie, a French engineer. His process consists in heating the glass to be toughened to a temperature close upon its softening point, and then plunging it into a bath of oil, or into a mixture of oleaginous substances kept at a much lower temperature. When this operation is successfully performed, the glass acquires properties very similar to those of Rupert's drops; it becomes much less fragile than ordinary glass, but when sufficient force is employed to fracture it, the whole flies into small pieces. It cannot be cut with a diamond, but is immediately disintegrated when the outer skin is scratched to a certain depth.
It is to be observed, however, that in particular cases it is possible both to saw and pierce the toughened glass. M. de Luynes reports, that when a square of St. Gobain plate glass that had been submitted to the process of tempering was examined by polarized light, it showed the appearance of a black cross, the arms of which were parallel to the sides of the square. The glass was sawed in two, along the line of the stem of the cross, without causing fracture. On examining the divided glass with polarized light, black bands and fringes of colour were observed, which, by their position, proved that the molecular condition of the glass had changed; on placing one half of the divided glass on the other half, the fringes and black bands disappeared—on folding one half on to the other, the black bands presented the appearance that would have been produced by glass of double the thickness. These facts show, that the molecular forces on the glass were arranged symmetrically in reference to the line of parting: and we may conclude that toughened glass being in a state of tension, similar to that of the Rupert drop, may be divided or pierced, provided that the molecules of the pieces produced are able to rearrange themselves into a stable equilibrium. Polarized light shows the directions on which the division can be made with safety.
M. de Luynes, in his communication referred to above, gives an account of some experiments performed on plates of glass of the same quality, tempered by this process, and untempered; one or two examples will suffice. A tempered plate measuring about  6½ inches by 5 inches, and 2/10 inch thick, was placed between two wooden frames, and a weight of over 3½ ounces (100 grammes ) was allowed to drop upon it from a height of more than 13 feet (4 mètres ) without breaking it. It only broke, when double the weight was employed from the same height. A piece of ordinary glass under the same conditions broke, with the weight of 3½ oz. dropped upon it from a height 16 inches (0·40 mètre). Plates of toughened glass were allowed to fall on the floor from a height, or were thrown to a distance, without breaking. A rectangular piece of ordinary window glass, about 1/10 inch in thickness, was bent into the form of a bridge, and then subjected to the tempering process; placed upon the ground; it bore the weight of a man easily without breaking. A commission, instituted by the French naval authorities, to inquire into this process of M. de la Bastie, has reported at some length on the subject. The following series of experiments were tried with a view of ascertaining the comparative power of resistance of tempered and ordinary glass. The plates experimented upon were placed loosely in wooden frames constructed for the purpose.
Rectangular plates about 21 inches (0·525 m.) by 10 inches (0·248 m.) and 1/6 inch (0·004 m.) thick.
The frame with the glass inserted was laid on the ground, and in the middle of the plate a weight of more than 10 lbs. (5 kilogrammes ) was placed, and upon it as a base, other weights were placed, care being taken to avoid all shock.
1º Ordinary glass, broke with a weight of about 70 lb. (35 kilos.) having resisted weights of from 30 to 50 lb.
2º Toughened glass resisted fracture until a weight of more than 510 lb. (255 kilos.) had been added, and then was not broken. The experiment was not carried to its limit for want of weights.
Rectangular plates, about 13 inches (0·325 m.) by 10 inches (0·248 m.) and 1/5 inch (0·005 m.) thick.
These plates were allowed to fall flat on to a floor of wood or thrown to a distance and allowed to fall.
1º Ordinary glass allowed to fall flat from a height of 1-2/10 inch (0·03 m.) was broken at the first trial.
2º Toughened glass. Thrown to a height 6 feet 6 inches (2 mètres) and to a distance of 13 feet (4 mètres) was also broken at the first trial. The piece, however, which had sustained the weight of 510 lb. did not break till the fourth trial.
Rectangular plates, about 10 inches (0·245 m.) by 6 inches (0·157 m.) and ¼ inch (0·007 m.) thick.
These plates were subjected to the same kind of tests as the foregoing. After raising them to a given height they were allowed to fall flat upon a wooden floor.
1º Ordinary glass raised to a height of 20 inches (0·50 m.) was broken on falling.
2º Toughened glass resisted successive falls of from 20 inches (0·50 m.), 32 inches (0·80 m.), 5 feet (1·50 m.), and 5 feet 7 inches (1·70 m.), but was broken when dropped from a height of 6 feet 6 inches (2·0 m.).
Rectangular plates about 10 inches (0·245 m.) by 6 inches (0·157 m.) and 1/5 inch (0·006 m.) thick.
Placed in the frames, they were held in position in the rabbets by laths nailed to the sides so as to prevent any play. The frames were raised to different heights and allowed to fall in such a manner as to cause as much vibration as possible.
1º Ordinary glass was broken with a fall of about 2 feet (0·60 m.).
2º Toughened glass resisted falls from heights of 3 feet 3 inches (1 mètre), 6 feet 6 inches (2 mètres), 8 feet (2·50 m.), 9 feet 9 inches (3 mètres), and 14 feet 6 inches (4·50 m.). It was only broken by a fall of 19 feet 6 inches (6 mètres).
Rectangular plates 6 inches (0·158 m.) by 4¾ inches (0·120 m.) and 1/5 inch (0·006 m.) thick.
These plates were placed in the frame on the ground, as has been previously explained. Known weights falling from known heights were made to strike the plates exactly in the centre. The weights consisted of bronze spheres, one weighing 3½ oz. (100 grammes) and another of twice that weight.
1st. Ordinary glass resisted the weight of 3½ oz., falling from heights of 8 inches (0·20 m.), 12 inches (0·30 m.), 16 inches (0·40 m.), but was broken by a fall of 20 inches (0·50 m.).
2nd. Toughened glass resisted the blow of the 3½ oz. weight falling from heights of 20 inches (0·50 m.), 40 inches (1 mètre), 60 inches (1·50 m.), and 6 feet 6 inches (2 mètres). The 7 oz. weight (200 grammes) being substituted, the plate was broken by it, falling from a height of 60 inches (1·50 m.).
Rectangular plates, 6 inches (0·158 m.) by 4¾ inches (0·120 m.) and 1/6 inch (0·004 m.) thick.
The same conditions were maintained as in the previous trial.
1st. Ordinary glass. The 3½ oz. weight was allowed to fall from heights of 1 foot (0·30), and 16 inches (0·40 m). It was broken by the second blow.
2nd. Toughened glass. This resisted the 7 oz. weight falling from heights of 2 feet 4 inches (0·70 m.), and 2 feet 8 inches (0·80 m.), but broke when the weight fell from 39 inches (1 mètre).
It appears then from these experiments, that toughened glass will resist a blow five times as great as ordinary glass, and will bear seven times as great a weight.
I have now detailed most of the useful experiments which have been made by competent observers upon toughened glass, as well as some which have been conducted in my own laboratory. The result of my own personal investigations I will now lay before the reader. I was consulted some time ago by a gentleman interested in the introduction of toughened glass into this country, as to whether this kind would become untoughened in time. I feel no hesitation in stating that when the process has been perfectly done, the glass will remain in the same state for any length of time, provided it be not treated in any way which is calculated to rupture the external hard bond that holds together the inner particles of the glass. I feel quite sure, that no fear of this kind need interfere with the benefits, whatever they may be, which are to be derived from submitting glass articles to the toughening process.
A tumbler which had been toughened in Monsieur de la Bastie's works, was, in my presence, thrown upon the ground, yet it did not break. It was a large soda water glass. I kept it for some time, and after considering the matter carefully, I felt, that if it were thrown down in such a way that the whole of its side, from base to rim, came in contact with the ground at once, and it then stood this test, it would prove that the whole of the glass was in the condition of the Rupert's Drops, and would therefore bear the concussion without fracture. I held the glass and let it fall, so that it actually reached the hard floor on its side. It immediately broke all to pieces. Now on the first occasion when this glass was thrown down, it was tossed somewhat upwards into the air, and the bottom being heavier reached the ground first, and it did not break. I have also seen in glass-houses, where the tempering process is carried on, tumblers thrown down in a similar manner, and I noticed, that whenever they fell upon their bottoms, they were uninjured, as also in cases where they fell upon their rims in such a manner, that the curve of the rim acted as an arch, as in the old trick of turning a wine-glass off the table so as not to break; but in other cases where the tumblers fell flat upon their sides, fracture followed. I carefully gathered together the pieces of the large tumbler which I broke myself in this manner, and examined them, and found that the solid bottom was broken in the same manner as the Prince Rupert's drops break, viz., into a large number of small pieces, having in all respects similar properties. The glass for an inch or two above the bottom broke into small pieces, but larger than those into which the bottom itself broke, and the upper portion of the tumbler was fractured just as an ordinary tumbler would be. On careful examination, microscopic and otherwise, the small pieces were found to have the character of Prince Rupert's, whereas the larger from the upper part of the glass had none of these characteristics in the slightest degree.
These observations led me to perform an experiment. A toughened tumbler was filled with plaster of Paris, which was allowed to set. Its outside was then encased in plaster of Paris, and when the whole was hardened, a pair of pincers were applied to a portion of the tumbler's rim, and with a violent wrench the tumbler was broken. A rather smart shock was communicated to the arm of the operator, very much resembling, as he said, the shock of an electrifying machine. On removing the plaster of Paris, it was found that the whole of the tumbler was fractured, and, as will be seen by the accompanying illustration, in a manner similar to that which has already been described.
From this and other similar experiments, I was led to the conclusion that none of the toughened articles which have cavities in them, have thoroughly undergone the toughening process.
Having been requested to attend a series of experiments performed by a glass manufacturer in London, which consisted in the manufacture of a number of toughened glass tumblers, I noticed certain facts which led me to form conclusions as to how it was that the tumblers, the fracture of which I already explained, break in this peculiar manner. I will first describe the way in which these tumblers were made and toughened. By the side of the glass blower there stood a metal vessel, about three feet six inches high, and, perhaps, from two to two feet six inches in diameter. This was filled with melted fat or oil of some kind at a temperature of about 80° Fahr. Inside this vessel, which was open at the top, there was a wire cage, with a trap door at the bottom about one foot in diameter, and of about the same depth. The glass blower, after finishing his tumbler on the pontil, held the pontil in a horizontal position over this metal vessel, struck it a smart tap, and the glass tumbled off into the wire cage. The glass was at a very high temperature. In almost every instance the glass fell into the melted fat, as a glass thrown in a similar manner will fall into water. It sank gradually bottom downwards, and the liquid guggled into it as it sank. Here, then, it is clear that every portion of the hot tumbler did not come in contact with the oil at the same moment, in fact there was an appreciable lapse of time before the tumbler disappeared beneath the surface of the liquid. Now there must be a limit as to the temperature of the article to be tempered and of the liquid by which it is to be tempered, that is to say, if at a certain temperature glass can be tempered by being plunged into the liquid of a certain temperature, if these temperatures are varied similar results will not follow. The upper portions of the glass coming in contact with the tempering liquid at a lower temperature, as they must have done, were not properly tempered, and this I have clearly proved by the facts I have already stated. From these remarks it seems tolerably clear that, until some method is devised of bringing all the parts of the heated glass in contact with the cooling liquid simultaneously, the tempering of the article cannot be perfect throughout its whole surface. As I desire, and very sincerely, that these processes should be brought to perfection so as to render them useful, I willingly give this result of somewhat lengthened investigations to those whom it may commercially concern, and I hope that they will find, on investigating the matter, that my observations have been tolerably correct, and that they will be able to devise a method which will remedy in many cases manifest imperfections of their present system. All the accidents which have happened to tempered glass, which have been recorded in the newspapers, can be accounted for on the principle which I have just endeavoured to explain, for there must be instability, where the bonding material of the internal particles of the glass is in different states of hardness; so that there is no difficulty in conceiving how a gas globe could break apparently spontaneously, for a portion of it which was not fairly toughened might be exposed to a somewhat sudden rise of temperature, produced, it may be, from a draught blowing the flame upon that particular spot. Articles such as saucers, made of glass, which, being flat, or nearly so, can be plunged into the tempering liquid with great rapidity, are usually tempered all over, and these, when toughened, can be thrown about and allowed to fall on hard floors with impunity, thus proving the facts which I have endeavoured to establish. I hope to be able to continue my investigations, and should they be worth anything, will give the results of them to the public. Before quitting this subject, I shall make a few remarks upon the process for toughening glass, which is said to have been purchased by the Prussian Government.
This process is described as consisting in the application of superheated steam to the glass, brought up to a temperature near to its melting point. Having facilities for making experiments of this kind, I have had them tried with great care, but in no case have I met with a satisfactory result. This probably is owing to the fact, that I did not comply strictly with the condition of the experiments performed by the German chemist who is said to have made the invention, nor do I see from analogy how this process is likely to effect a change in the glass similar to that arising from M. de la Bastie's dipping process.
If glass, instead of being taken from the annealing kiln at the proper time, be left exposed in the hot part of it, at a temperature just below that at which it softens, it will be found to become gradually opaque on its surface. Some experiments were performed many years ago by Réaumur, who exposed pieces of glass, packed in plaster of Paris, to a red heat, which became gradually opaque, and lost altogether the character of glass, the texture of their material becoming crystalline, and also effected by sudden changes of temperature. Glass treated in this way was called Réaumur's porcelain. All glasses do not undergo this change with equal rapidity, and some do not experience it at all; but the commoner kinds, such as bottle glass, are the best to experiment upon, for the more alumina that it contains—and it is known that bottle glass contains a considerable quantity—the more readily does it undergo this change, which is called devitrification. In what it consists, is not at present well understood, but it offers a field for investigation, which may produce results of very considerable benefit to manufacturers of glass.
Soluble Silicates.—An article on glass in a modern scientific work like the present would not be complete without a notice of the manufacture of soluble glass and the uses to which it has been and may be applied. It has already been mentioned that when silica or sand is fused with an excess of alkali, the resulting glass is soluble in water.
Soluble glass is made on a large scale in three different ways. First of all, if flints, that is, black flints, which are found in chalk, be heated to a white heat, they lose their black colour and their hardness, and are easily crushed to small pieces; and if flint in this condition be placed in a wire cage and put into a jacketed iron digester, that is, an iron digester which has an inner and an outer skin, with a free space between the two, so that steam may be forced into it from a boiler under pressure; and if the digester be screwed down tightly with an iron cover, and steam then be allowed to pass into the space between the two, the temperature can be raised at pleasure, according to the pressure under which the steam is introduced. If the valve of the boiler be loaded with a 60-lb. weight, the temperature of the water warmed by the steam will rise considerably higher than that of ordinary boiling water; and if this water be saturated with caustic soda, it will dissolve the flints slowly, forming silicate of soda, that is to say, the silicic acid of the flint will unite directly with the soda of the solution, and silicate of soda will thus be obtained. For certain applications, the silicate so formed is not sufficiently pure, because the soda used often contains a certain amount of sulphate, which will remain with it in the solution of silicate that is drawn off from the digester. This sulphate is very objectionable for certain applications of silicates, because it crystallizes out, and so destroys the substance, which the silicate is intended to preserve.
Another and a much better method is to heat together the silica in the form of sand with alkali, either potash or soda, in a reverberatory furnace, and as the glass becomes formed, to rake it out into water, and then gradually to dissolve it by boiling in suitable vessels. Here the sulphate, if it existed in the alkali, is decomposed by the silicic acid, and the sulphuric acid passes off through the flues of the reverberatory furnace.
There is also a very ingenious way of making silicate of soda, discovered by Mr. Gossage, and performed as follows: common salt is heated to a high temperature and volatilized, and in this condition is brought into contact with steam also at a high temperature, when a double decomposition takes place. Steam is composed of oxygen and hydrogen; common salt, of sodium and chlorine. The chlorine of the common salt unites with the hydrogen of the steam, and the oxygen of the steam with the sodium, so that hydrochloric acid and oxide of sodium are formed. Now, if these two substances at this high temperature were allowed to cool together, the action would be reversed, and the re-formation of steam and chloride of sodium would be the result; but in the strong chamber lined with fire-clay, in which these vapours are brought into contact, silica is placed in the form of sand made up into masses, and when the oxide of sodium is formed, it unites with the sand to make silicate of soda, and thus is removed from the action of the hydrochloric acid, not entirely, but sufficiently to produce a large yield of silicate of soda.
The properties of silicate of soda, as applied to the arts, are somewhat different from those of silicate of potash, so that one cannot always be substituted for the other. Both these substances are, when in solution and concentrated, thick and viscid, and have the property of causing paper, wood, &c., to adhere when applied as a gum or glue, and hence have been called "mineral glue." In a dilute state they can be used for coating stone, brick, or cement, and have the power of rendering them for a time waterproof, or nearly so, and of preventing the action of atmospheric influences, which too often produce the decay of some of the softer stones used for building as well as for cement. It has already been stated, that when carbonic acid is passed through a solution of silicate of soda, silica will be precipitated. Now, inasmuch as there is carbonic acid in atmospheric air, when these solutions are applied to the surfaces of a building, they will be acted upon slowly by the acid, and silica will be precipitated in the pores of the material to which the silicates are applied. But this operation is extremely slow, and, before it can be thoroughly completed, the silicates, being soluble, will get in part dissolved out by rain and moisture, and it is therefore advisable to use with them some material which will, by a double decomposition, form a silicate insoluble in water. The silicate, however, which is formed, should have cohesion amongst its particles, so that it will not only adhere to the stone itself, but its own particles will adhere to one another when it gets dry. Various methods have been tried to cause this insoluble substance to be formed upon the surface of stones, so as to fill up its pores and to make a protecting cover for it; but most of them have signally failed, because the new silicate produced by double decomposition has not had the necessary coherence amongst its particles. If a solution of chloride of calcium be added to one of silicate of soda, a silicate of calcium will be precipitated, and it was therefore thought, that by applying to a stone successive washes of silicate of soda and chloride of calcium, an insoluble silicate of calcium would be produced in the pores and on its surface. It is true that such a silicate is precipitated, and that, if the silicate employed be in excess of the chloride of calcium, the particles will be glued together by the adhesive powers of this silicate when it dries; but then the action of moisture upon it is to cause it to run down the surface of the building, and set free the particles of silicate of calcium which it held in combination. Other processes of the same kind have been tried, and with similar results; one great difficulty in the way of the success of this method of applying silicates being that, from the peculiar colloidal or gluey nature of the silicate, it does not penetrate to any considerable depth into the stone, and, if laid on first, prevents the penetration, as far even as it has itself gone, of the solution of chloride of calcium. If the chloride of calcium be used before the silicate, it will penetrate farther than the solution of silicate is able to reach, so that it is impossible to obtain, even supposing the substance to be used in equivalent proportions, a complete decomposition of the one by the other.
The great object to be attained in the preservation of stone by any silicious process, is to use one solution possessing the substances which, when the water has evaporated, will form a perfectly coherent mass for the protection of the stone surface. The depth of penetration, if it is sufficient to protect the outside of the stone from the disintegrating action of the atmosphere, need not be carried much more than one-sixteenth of an inch below the surface, for when old stones which have long been in positions in buildings, and which have not decayed at all, are examined, it will be found that they are covered with an extremely thin film of a hard substance, not thicker than a sheet of writing paper, which has for ages protected and preserved them from decay. This film is produced by a determination from the inside to the outside of the stone of a silicious water, which existed in it in the quarry, and which, when the stone was placed in the building, gradually came to the surface, the water evaporating and leaving behind it a thin film of silica, or of a nitrate—most likely the latter.
If alumina be fused with potash, aluminate of potash, soluble in water, is made; if, however the solution is too concentrated, a certain quantity of the alumina will be precipitated; but if it be dilute, the whole of the alumina will remain in solution. When aluminate of potash of specific gravity 1·12 is mixed with a solution of silicate of potash of specific gravity 1·2, no precipitate or gelatinization will take place for some hours; the more dilute the solution, the longer will it remain without gelatinization, and of course the thinner it will be, and the greater power of penetration it will have when applied to a porous surface. When solutions of aluminate of potash and of silicate of potash of greater density are mixed together, a jelly-like substance is almost immediately formed, and sometimes even the whole mass gelatinizes. If this jelly be allowed to dry slowly, it will contract, and at last a substance will be left behind sufficiently hard to mark glass, though the time for this hardening may be from one to two years; and on examination it is found that this substance has very nearly the same chemical composition as felspar, and is perfectly insoluble in ordinary mineral acids. Now, suppose a dilute solution of this mixture to be applied to the surface of stone, the silicate and aluminate of potash will gradually harden and fill up the interstices of the stone; and as both the substances entering into combination are contained in the same solution, they will both penetrate to the same depth. Inasmuch as the artificial felspar is not acted upon by destructive agents which would disintegrate the stone, it becomes a bonding material for its loosened particles, and at the same time gives a case-hardening to the stone, which no doubt will as effectually protect it against atmospheric influences as in the case of the hardening of the natural one. We have a tolerable guarantee that this will be so, if we consider the number of enduring minerals into the composition of which silica, alumina, and potash enter, and also of the almost imperishable character of granite, which is so largely composed of felspar. Many experiments have been performed on an exhaustive scale with these materials, and in every case it has been found that they have answered the expectation of those who have thus tested them. It is, however, necessary to state, that in making these experiments, great care must be used to employ the mixed substance in solution before gelatinization has set in, for if this has occurred, even to the slightest extent, a surface coating is formed on the stone, which, not having formed a bond with it, easily rubs off.
Another application of soluble silicates in this or other forms is to render walls of buildings which are porous, waterproof. A colourless, transparent material which can effect this object is doubtless desirable, as anything like an opaque wash, if applied to brick-work, would destroy the colour of the bricks, and therefore the character of the building constructed with them. The silico-aluminate of potash may be used for this purpose, as above directed; and even silicate of potash alone, provided it be in sufficient quantities, will answer well, if from year to year, for two or three years, the application be renewed, so as to fill in spaces, wherever the silicate may have been in part dissolved out. When the silicate of potash alone is used, the action of the carbonic acid of the air in precipitating the silica is depended on, and while this action is going on, portions of the silicate not acted on will be dissolved out.
Many years ago, an effort was made in Germany to revive the ancient art of fresco painting, and with very considerable success. It was found, however, that our climate is not suited to the permanence of this method of decoration, nor indeed is any climate absolutely suitable, because in fresco painting, the surface only of the lime is coloured with pigments laid on, so that any influence which would destroy the lime surface would cause the removal of the pigments; and from the porous nature of the surface of the work after it is completed, absorption of moisture will from time to time take place, causing the adhesion of dirt and other foreign substances which may fall upon it, and which it is almost impossible to remove without detriment to the picture. Dr. Fuchs, of Munich, discovered a method of painting with soluble silicates, which has been tried with considerable success in Berlin by the late Professor Kaulbach. On a properly prepared ground, the painting was executed in colours mixed with water, which, when dry and the painting finished, were fixed to the wall by the application of soluble silicates. For the preservation of the work, Dr. Fuchs mainly relied upon the action of atmospheric carbonic acid. Now, when carbonic acid acts upon silicate of soda or silicate of potash, we have already seen that the silicic acid is precipitated in the hydrated form, and that the carbonic acid has united with the soda or potash to form carbonate of soda or carbonate of potash. These substances being left in the painting and penetrating to a certain depth beneath its surface, must find their way out, and in almost every instance have done so in the form of an efflorescent substance, which has caused the picture to have the appearance of being mildewed over its surface. Sometimes, however, sulphates occur in the ground, and then sulphates of soda and of potash have been formed, injurious to the permanence of the surface of the picture, because they crystallize and force off portions of the lime and sand of which the surface is composed. The effect of the efflorescence of the carbonates on the surface of a silicious painting may be seen in the famous picture of the meeting of Wellington and Blucher, in the House of Lords, painted by the late Mr. Maclise, R.A. When, however, the solution of aluminate and silicate of potash is used with the pigments on a properly prepared ground, there is no fear of this efflorescence taking place, and paintings executed with it have stood for many years, without giving any signs whatever of decay.
To those interested in this subject, it is desirable that they should perform a series of experiments themselves, and ascertain the best methods of practically applying this vehicle in the execution of large mural paintings. They will find that, although at first they may meet with some difficulties, yet after a while these difficulties will vanish, and they will have a material to work with, which will meet all their requirements.
In an article so brief as the present, it is impossible to enter fully into all the details of the manipulation of this particular process of painting; it is, however, most desirable to give a short account of the method of preparing the ground and of applying the colours, leaving the rest to be learned from practical experience.
Angular fresh-water river sand, well washed, should be mixed with sufficient lime to cause it to adhere to the wall on which it is placed, and this in all cases should be freshly plastered in the ordinary way. No plaster of Paris (which is sulphate of lime) should be used in the preparation of the groundwork. The coating of fine sand and lime is laid on to a depth of about an eighth of an inch, and when dry, an application of dilute silicate of potash should be made, in order to bond together the particles of sand which, owing to the employment of so small a quantity of lime, can be readily brushed off. As soon as these particles are well fixed together and do not come off when the hand is passed over the surface of the wall, the ground is in a fit state for the commencement of the painting. The colour should be used with zinc white, and not with lead white, and, of course, they must be in the state of fine powder, and not ground up with oil or any such material. The artist can use his mixture of silicate of alumina and aluminate of potash of the strength already described; he may, when desirable, dilute it to a certain extent with water, but he should not do so too much. He can then paint with it just as he would with water in water-colour painting; and if he finds that any portion of his colours, after they are dry, are not sufficiently fixed upon the wall, he can then with a brush pass over them a coating of the clear liquid, used a little stronger. When the whole work is finished, it will perhaps be desirable to give it one or two coats of a very dilute solution of silicate of alumina and aluminate of potash. After a time, owing to the contraction in drying of this material, it would be advisable—say, after the lapse of two or three months—to again apply a coat of it somewhat stronger; and again, if after a year, or more than a year, it should appear that any portions of the surface were becoming loose, another application of the mixed silicate of alumina and aluminate of potash to these loosened parts alone will be desirable. This repetition may appear to some to be an objection to the process, but it is not so, however; for in the formation of those natural substances, such as flints, which we find so hard, no doubt a very great lapse of time occurred in the induration of the gelatinous silica which formed them. Neither do we object from time to time, at intervals of years to renew the coats of varnish on oil paintings, in order to preserve them or to bring out afresh the brilliancy of their colours.
The soluble silicates are frequently used as bonding materials in the manufacture of artificial stone and cement, very good results having been attained. The objection, however, to their employment for these purposes is the expense of the material of which they form a constituent part, and it seems almost impossible ever to bring it into competition with dressed natural stone. But for ornamental purposes, from the plastic nature of the substance when in the wet state, it can be pressed into moulds, and wherever plaster mouldings are admissible, no doubt this material would be useful for certain kinds of ornamentation. Some years ago, Mr. Ransome, of Ipswich, after having made his artificial stone with sand and silicate of soda, heated it in ovens, so as to produce a hard and semi-vitrified mass. A church, the mouldings of which are made of this stone, may be seen at the bottom of Pentonville Hill, London; and certainly as to durability, there is no doubt that the substance has answered very well. But from difficulties in manipulation and other reasons, that gentleman gave up this method of making artificial stone, and is now working another process which yields far better results. Silicate of soda is mixed with sand (generally Aylesford sand), and after the mixture is moulded and dried, it is exposed to the action in vacuo of chloride of calcium in solution. Whether the whole mass is placed in a vacuum chamber and then charged with chloride of calcium; or whether a vacuum is formed on the under side of the substance, and the chloride of calcium solution caused by suction to filter through it, is uncertain. However, whatever be the manipulative processes, the result is the same, and appears to be extremely satisfactory.
Soluble silicates produce very remarkable results when mixed with certain substances. If silicate of soda or potash be mixed with white lead, in a very short time it sets into a hard substance, just as does plaster of Paris when mixed with water. If powdered pumice-stone or sand, in the proportion of eight parts to one of carbonate of lead, be mixed together with soluble silicate, a very hard and coherent mass is obtained, and there seems no reason why a mixture of this kind, in which pumice-stone is used, should not be employed for the purpose to which pumice-stone is usually applied. It would have the advantage of being easily moulded into forms, so as to suit mouldings, which might by it be much more accurately and expeditiously smoothed down (as in the case especially of picture-frame mouldings), than they can be by the ordinary pumice-stone.
Another very important application of soluble silicates is the rendering of wood incombustible. Many experiments have been performed which show that when wood is thoroughly impregnated to a depth of a quarter of an inch or more with silicate of soda, it will not flame, but will only char. Now, supposing that the constructive timbers of a house were worked, and then placed in suitable vessels and saturated with silicate of soda, they would then be rendered practically fireproof, or at least it would take a very prolonged exposure to heat to cause them to smoulder away, while at no period of this time would they burst into flame. From the peculiarly gluey nature of these soluble silicates, they do not penetrate readily into porous substances; it has therefore been suggested that the impregnation of the wood should take place in vacuum chambers, just in the manner that the creosoting process for preserving railway sleepers is at present performed. It is most certainly advisable that the wood should be worked before being exposed to the silicating process, for that would render it so hard, that it would considerably increase the cost of labour in cutting and planing it.
At the commencement of this article, it was stated that silicic acid, or silica, could be made soluble in water. Some very interesting experiments were performed by the late Dr. Graham, Master of the Mint, which gave rise to the discovery of the process of dialysis. If some silicate of soda be mixed with water, so that not more than 5 per cent. of silica be in the solution (rather less is better), and if some hydrochloric acid be then added in sufficient quantity to make the liquid distinctly acid, and the mixture be placed in a dialyzing apparatus, the chloride of sodium formed by the union of the chlorine of the hydrochloric acid with the sodium of the silicate of soda will pass out through this dialyzing membrane, leaving hydrated silica behind, which will remain in solution in the water with which the silicate was mixed. The dialyzing apparatus is constructed in the following manner; a sort of tambourine ring is made with gutta percha, in place of wood, from 8 to 10 inches or even more in diameter, the depth, being about 2 inches. Another ring of gutta percha, of about an inch deep or even less, is made so as to fit tightly outside the tambourine; a piece of vegetable parchment is then moistened and placed over the tambourine, and the thinner ring is pressed over it, so as to secure it tightly. This is the dialyzing vessel, and it is into this that the mixture of silicate and hydrochloric acid must be put. The solution should not be more than an inch deep in the dialyzing vessel, which is then made to float upon distilled water in a larger vessel of suitable size. The distilled water should be changed every day, until no precipitate can be obtained in it with nitrate of silver, and when this point is arrived at, all the chloride of sodium will have passed through the vegetable parchment into the larger vessel of water, and nothing but silicic hydrate will remain behind in solution. If this liquid be allowed to stand for some time, it will gelatinize, and later on the jelly will contract, becoming extremely hard, so that lumps of it, when broken, will in their fracture resemble that of flint. No doubt, at some future period, some one will discover a method of rendering this condition of silica useful in the arts.
Soluble silicates are very useful as detergents. A small quantity of silicate of soda mixed with hard water renders it valuable for washing purposes. Silicate of soda is also used in the manufacture of the cheaper kinds of soap. We can hardly speak of it as an adulteration, because it renders the soap with which it is combined much more powerful in its cleansing action. I suggest to those interested in the application of science to the arts, that this subject will no doubt well repay experimental investigations.
It is much to be wished that those engaged in this branch of art and manufacture, and who have some knowledge of chemistry, would turn their attention to getting a better and more perfect method of making coloured pot-metal glass. I have been engaged for some time, and still am engaged, in experiments to effect this object. But inasmuch as my engagements are very numerous, and I cannot give the proper time to it I desire, I therefore take the liberty of suggesting to others the ways in which I am working, that they may be able to arrive at good results more speedily probably than I shall be able to do. If sulphate of copper be mixed with silicate of potash, silicate of copper will be precipitated. Now, if this be carefully washed and dried, it will be a silicate of a definite composition, and I propose to use such silicates as these with ordinary glass mixtures, in order to impart the particular colour which the oxide employed has been already described as giving to the glass. Silicate of manganese is prepared in a similar way to the silicate of copper; silicate of cobalt, and other silicates, can be used as staining materials for colouring glass. These mixed in due proportion would give tints, and would, I do not feel the slightest doubt, produce colours with much greater certainty than they are now produced, and tints hitherto unknown could be made to the great benefit of the glass-painter.
FURNITURE AND WOODWORK.
By J. H. Pollen, M.A., South Kensington Museum.
I propose in the following pages to give some account of the materials used in making furniture, and of the arts applied to its decoration. From the earliest ages of society, when men moved about in tribes, they had in their tents of camels' hair simple necessaries, such as their wants required. Before people were gathered into distinct nations, or cities built with walls and gates, there were still certain human wants that must needs be supplied; and the objects that were needed to enable mankind to live with convenience and decency were found in their furniture. To this very day we may see Arab tribes wandering over sunny deserts, seeking pasturage, sowing here and there an acre of wheat or barley, or gathering dates. Their camels and dromedaries are their waggons, their horses are their friends, their families and those of others that make up their tribe are their only nationality. Yet they furnish in some sort the temporary homes which they shift from one spring of water to another, as the patches of grass or grain grow up and ripen. Their chief wants are, a cloth strained over three staves to make a house, mats or carpets to lie on, a few bowls to cook in, saddles of wood, and a few baskets or chests, made of light sticks fastened together.
In later periods of history and in more conventional states of society, we shall find this primitive type of furnishing carried out with growing splendour. In the West and in the East, in ancient and mediæval times, great rulers, though constantly in the saddle, have been followed by enormous trains of camp followers, by whom costly furniture, hangings, vessels of plate, and other luxuries, have been carried for the convenience of the leaders and warriors of moving hosts; and of course this splendour was the measure of the state and magnificence kept at home. The wealth or feudal state, shown in the furniture of old castles and palaces, extended not only to halls and rooms, but to dresses, and armour, weapons, the furniture of horses, tents, and other objects that could be carried on distant expeditions.
Ancient nations have been as well, and more splendidly, if less conveniently, provided with furniture for their houses than modern ones. It happens that there are distinct records of many kinds, showing what wealth and elaborate decoration some of the oldest races, such as the Assyrians, the Egyptians, the Persians, and the Greeks, bestowed on their thrones, beds, chairs, and chariots. Beds of silver and gold are mentioned in Esther i., and the curtains of the bed of Holofernes were covered with a canopy of purple and gold, with emeralds and precious stones (Judith x. 19; Esther i.). Modern princes in India continue to devote their jewels and gold to similar uses. It must be borne in mind also, that this kind of splendour is an investment of property in times and countries in which banks, insurance offices, government funds, and other organized means of investing money are unknown.
Silver, if not gold, has been used occasionally, not only in the East, but in Europe, for seats, tables, even the frames of pictures and mirrors. The royal apartments in Whitehall were completely mounted with hammered and filagree silver furniture in the seventeenth century. Carlyle records of Frederick the Great, that silver ornaments were kept in his palace, and turned to account under the exigencies of war. But of furniture generally, wood is the readiest and most proper material. It is handy, easily worked, light to carry about, and may be manufactured with or without decorations of carved work, or of any other kind. Hence, in giving an account, whether historical or mechanical, of furniture, I class it under the more general head of woodwork. Any other materials, either for the framing or ornamentation of furniture, are exceptional. The remarks now to be submitted to the reader will refer to wood that is manufactured, though I shall not enter on the interesting subject of wood structure, which has been applied to such noble and elaborate uses, and of which such splendid monuments of many periods still remain for us to study.
Most of the methods used for decorating woodwork made up into furniture are still in regular use, and the processes of putting it together are the same as they have always been. The reader may satisfy himself on this point any day by a walk in the Egyptian rooms and in the Nineveh galleries of the British Museum. In both these sections of that wonderful collection, there are remains of woodwork and of furniture, made of wood three or four thousand years old, such as stools, chairs, tables, head-rests or pillows, workmen's benches of Egyptian manufacture, fragments less complete of Nineveh make that have been portions of various utensils, and precious articles of sculptured and inlaid ivory that have been inserted into thrones and chariots. These pieces of furniture have been mortised together, or joined by dowels, dovetailed at the angles, glued, nailed, or, in short, made up by the use of several of these methods of junction at the same time. And no great changes have been introduced in the various ways of ornamenting furniture. The Egyptian woodwork was painted in tempera, and carefully varnished with resinous gums. It was inlaid with ebony and other woods, carved, gilt and, perhaps, sparingly decorated with metal ornaments. The Greeks inlaid chests and tables with carved ivory and gold, sometimes relieved with colour. The Romans, who made much furniture of bronze, cast, inlaid, damascened and gilt, made much more in wood, which they stained, polished, carved, and inlaid. Mediæval furniture was put together with mortises, tenons and glue, and was gilt and painted; the painting and gilding being laid on a ground prepared with the utmost care, and tooled and ornamented in the same way that bookbinders ornament leather. At a later period, a beautiful manufacture was carried on in various parts of Italy; a sort of mosaic in very hard stone, such as agate, lapis lazuli, and other precious materials. The Italians also used these beautiful stones inlaid in ebony. But the furniture most valued in modern times has been that which owes its name to Boulle, a French artist of the seventeenth century; and the marquetry, or wood mosaic surface decoration, which reached so high a standard of excellence during the last thirty years of the eighteenth century in France.
The former of these two classes of manufacture made, if not originated, by Boulle (and I am inclined to think that he was not the first maker), was a marquetry, or surface decoration, not composed of various woods, but of tortoiseshell and brass, with the occasional introduction of other metal, and with metal enamelled in blue and other colours. The materials principally in use, however, in Boulle marquetry are tortoiseshell and brass. In the older work, viz. that of the seventeenth century, the tortoiseshell is dark, and left in its natural hue. In later Boulle, called new Boulle, the tortoiseshell is reddened by colour, or by gilding laid under it. There is much grace and variety in the delicate arabesque designs in which one material is inlaid in the other. Parts of the surfaces are sometimes diapered, as a contrast to the free lines and curves of other parts. The inlaid surface of Boulle work is framed in by borders, cornices, or handles of brass or gilt bronze, giving a massive architectural character to the whole.
Thus if we look back to the history of furniture, not only will every kind of splendid material be found devoted to the manufacture or decoration of it, but the best art too of many different periods that money could command. It is in the late times of antiquity, and since the period of the Renaissance in modern times, that works of art have been kept on shelves or gathered into galleries. Many works of great masters, such as the chest of Cypselus, and the chairs of the great statues of ivory and gold, were prepared for celebrated shrines and temples in the cities of Greece. It was but the excessive wealth of great patricians in Rome and Constantinople that led to their becoming collectors, whether of sculpture, painting, or sumptuous silver plate. The chief object of rich and accomplished men in most ages of luxury and refinement has been, to make the house, its walls, ceilings, floors, and necessary or useful furniture, costly and beautiful. It was the same in the days of Donatello, Raphael, Cellini, and Holbein. Chests and trays were painted, together with gems, dies, brooches; table plate was modelled and chiselled; while chairs of wrought steel, or tables, cabinets, and other pieces of rich furniture, were either designed or carried into execution by these masters with their pupils and followers. In some instances, as, e.g., in that of the famous Pomeranian cabinet, in the Kunst Kammer in Berlin, a long list has been preserved of artists and craftsmen of note in their day, who combined to produce monumental examples of actual room furniture.
It cannot be denied that though great pains are taken and much expense is incurred in modern furnishing, the habits of the day lead rather to the search for comfort than for grace or beauty; and convenience rather than intrinsic value or artistic excellence. Nevertheless, a certain amount of decency and splendour is indispensable in both receiving and sleeping rooms; and though a house really well, that is beautifully, furnished is of rare occurrence, this is not for want of serious efforts, nor altogether to be laid to the account of unwillingness to spend money for such a purpose. Whether the "art of furnishing" or the desire to have what people require for use in their houses more becoming and beautiful, be a rising influence or not, it is certain that the "fancy" or ornamental furniture trade is of large and increasing importance, corresponding to the increased size and cost of modern London and country houses, compared with those built during the reigns of William III. and George IV. Every tradesman who has the pretension to repair chimney-pots, to whitewash, or paint house-fronts, ceilings, or offices, writes up the word "decorator," on his shop-front.
The Qualities required in Furniture.
We may consider furniture under two broad divisions, that which is made to be handled and moved about, and that which is for use but not meant to be handled or moved. We may add a third division in the actual fixtures of the house, made by the joiner and meant to be ornamental fittings or completions to the builder's and carpenter's work.
Under the first head will be included light tables, chairs, couches, and other movable objects; under the second, cabinets, book-shelves, frames, mirrors, and so on; under the third head come flooring, panelling, window shutters, door-frames, stair-rails, &c.
1. Chairs, Tables, etc.
The essential points in a well-made chair are comfort, lightness, and strength. Of course, as men and women are pretty much of the same proportion all over the world, chairs, of which the seat is about the height of the lower process of the human knee-joints, must be of the same height, or but slightly varied, in every country. From the habit that so many persons have of throwing their whole weight back and, as we are told, in some countries, of balancing their persons on the back legs of their chairs and inclining their legs in the direction of the chimneypiece, there is often an immense strain on the back joints of chairs. Whether we lean back or swing on them, the junction of the seats of chairs with the backs is always subject to severe trials; and on no article of furniture in common use is such good joinery required. It is worth while to look at the old wall paintings of the Egyptians, as they are given in Rossellini and the great French book of the 'Description de l'Egypte,' to see what capital workmanship those most ancient carpenters bestowed on their chairs. Those of the best and oldest periods are without connecting bars to the legs before or behind, all the strength of the construction being centred in the excellence of the joints of the seat with the back and legs; and in modern workshops, the highest skill is applied to ensure strength in these points of junction. If the wood is thoroughly dry, the mortises and tenons fitting perfectly, and the glue good, the different parts are so wedded together that the whole structure becomes one piece, as if nature had made a vegetable growth in that fashion, all the fibres of which have continuous and perfect contact with each other. If, however, there is a deficiency in any of these conditions, these joints fail. If the wood shrinks, or the tenons do not fit the mortises all through, or the glue is deficient, these various portions speedily come to pieces. Sofas, couches, and stuffed chairs are so much more massive in construction that there need be no risk of such a kind of disintegration.
The members of which a chair is made up may be either turned in the lathe, or left massive enough to allow of carving on the legs, backs, or round the framework of the seat. Turned work can be lightly inlaid with ivory, as that of ancient Egypt, painted, gilt, or mounted (lightly also) with metal.
The subjects of the carving may be either figures of men, horses, lions, or the heads and legs of such animals, acanthus leaves, and arabesques. Many of these ornaments have been used from ancient times, and revived at various historical periods. For modern rooms the lightest construction is most in place, and therefore carving should be compact in composition and delicate in execution, without prominences or undercutting that would interfere with comfort or be liable to breakage.
A certain architectural character is given to chairs by cutting flutings down the legs, or by borrowing other slight details from architecture. The upholstery of chairs will always be their most noticeable decoration, and this applies still more to lounging chairs and couches of all shapes and sizes, as the framework of them is so much less observable in proportion to their upholstered surfaces.
Tables, lampstands, &c., being generally, though not always, meant to be moved about, require as light a construction as is consistent with strength. The surface of all but small tables is beyond the dimensions of a single plank of wood. The outer and inner portions of a log or plank are of different fineness of grain, contain varying proportions of sap, and shrink in different degrees. Single planks of wood, therefore, can only be exceptionally used for table tops. Generally, they are made up of portions of planks selected with great care, grooved on the edges, with a tongue or slice of wood cut the cross way of the grain, uniting the planks about the middle of their thickness; the edges are then firmly glued together. If the surface is to be of wood which can be procured in large pieces of straight or continuous grain, such as mahogany, the wood is solid throughout; if of some rare wood or rare figured graining, such as the roots or wens of oak, this ornamental surface is laid on in thin slices with glue and heavy pressure. This is known as veneering. The surface is sometimes inlaid with ivory, metal, mother-of-pearl, slices of agate and other substances, as in the Boulle or marquetry work already alluded to.
The frame of the table is either a deep rail not far within the edge, or a thick pillar or leg or several legs collected, mortised into a broad expanding foot and supporting a spreading framework above, to which the top itself can be fastened, and stretching far enough all round in the direction of the edges to give a firm support.
The decoration of the top can only be superficial if the table is for use, and any decoration by carving, piercing, and so on, must be confined to the framework and the supports. These parts can be, and have been at all times decorated as the framework of chairs, and by very much the same kinds of ornament.
To tables of more modern periods, little galleries of pierced work or of tiny balustrades are sometimes added. They belong to the age of porcelain collectors, hoops, broad coat-skirts, and tea-parties, and are intended to save delicate wares from being swept to the ground. Side tables, and such as are made to support heavy objects, can be treated with more massive frame work and supports, and the carving and decorations will be bolder and larger accordingly.
2. Cabinets, etc.
I will proceed to the second division of furniture, cabinets, bookcases, and other standing objects, which are more or less immovable. But shelves and china trays must be placed in secure parts of the room, if they are not actually fastened to the wall. The former must be strong to support the great weights laid upon them, and the supports or framework, which is all that would be seen, may be carved or decorated with surface or applied metal ornament. On a large scale, fittings of this kind belong rather to architectural woodwork. China holders, whether placed on the ground or fixed against a wall, are properly treated with shelves quaintly shaped on plain and light, pierced galleries or gilt decorations corresponding with the apparent lightness of pieces of porcelain. The wood and lac work cabinets of the Chinese; and the complicated, but not ungraceful, gilt mirror frames and flourishing acanthus work of the Italians, French, and Germans, of the last century, seem specially suited for showing off this gay and fragile material. The collector proper will probably place his treasures under glass, and with little regard to the framework of his cases. Here china and china stands are treated only as decorations.
As to cabinets, they are the most precious, if not the most useful of all pieces of furniture. They have generally been intended to hold family treasures, are not required to be moved, and have therefore been the richest and most decorated objects in the room. Cabinets are the legitimate descendants of the chests of former days containing bridal outfits and trinkets, or plate, jewellery, and other valuables. They were carried from town to country, from grange to castle. About the beginning of the sixteenth century, the personal habits of great men became less nomad, and their chests were no longer liable to be packed and moved away. These receptacles were mounted on stands at which height the lids could not be lifted, and doors were substituted. Drawers took the place of shelves or compartments, and every sort of ingenuity was applied to make these pieces of furniture quaint and splendid inside and out.
As to shape, it is contrary to their purpose of convenience and interior capacity, to make cabinets, cupboards, or other receptacles, with showy and spreading architectural details, such as cornices, architraves, columns, pediments, and the like. All these parts, which are laborious and costly in construction, are so many additions to its size, and make no more room inside to compensate for this expenditure. Cabinets should, in propriety, be as big and convenient inside as their size would lead us to expect.
On the other hand, the many fine examples made in the sixteenth and seventeenth centuries in this country, Holland, Germany, France or elsewhere, have been generally intended for rooms larger, higher, and with fewer pieces of furniture in them than those of our modern houses, not to speak of the massiveness of fireplaces and fittings with which they were in character. It is their age, and the connection, which we cannot help tracing, with old houses and bygone generations which give architectural cabinets an interest now.
In construction, the skill of the cabinet maker will be shown in the neat and convenient arrangement of drawers of various depths and sizes, shelves or repositories, so contrived as to turn the entire internal space to account. The most curious contrivances are often found in old German, English, and French cabinets, bureaux, secrétaires, and other varieties of this kind of furniture. Pediments, capitals of columns, and other parts of architectural fronts are made to open, and secret drawers stowed away with an ingenuity almost humorous. It is upon the fronts and stands that the skill of great masters of the craft has been bestowed. The large wardrobes, or "armoires," of Boulle are examples of great inventive and designing power, as well as the marquetry of Riesener and David, and the chiselled metal-work of Berain, Gouthière, and that of many English artists.
As in past times, and so in our own, it is on cabinets that the real triumphs of the cabinet maker's art are displayed.
3. Fixed Woodwork.
Thirdly, the joiner's and cabinet maker's art plays an important part in the fixed furniture of the house, and the woodwork, such as flooring, doors and door-frames, panelling, chimneypieces, with the complementary decorations of hangings, whether tapestry, silk, or the more humble material of paper.
In this last division of furniture the work is that of joinery. There is no great demand for constructive strength, as the work is fixed to walls; but as doors and shutters are swung to and fro continually, and subject to jars and strains, their stiles and rails, upright and cross-framing members, as well as the panelling that fills them, require well-seasoned timber and the most accurate workmanship: without these conditions the joints open, the panels shrink from the grooves in which the edges are held, and split, while the frame itself, if of unseasoned material, 'buckles' or twists, so that the door or shutter will no longer shut flat in its frame.
Panelling and fireplaces are, however, opportunities for the display of carving, inlaying, and gilding. The reader has seen carved room panelling, probably, in many old houses. In some of the municipal 'palaces' in Flanders, e.g. in Bruges, and in the old rooms of the Louvre in Paris, carved panelling of the utmost grace and perfection, some of it in groups of life-sized portrait figures, may be studied by the tourist.
Of work so rich and costly as this wood sculpture, it is perhaps hopeless to speak with reference to our modern houses, and in connection with the manufacture of furniture in this country, at least on any large or general scale of application. Still as such work, confined to the composition of fireplaces or sideboard backs, is still sculptured by Italian and French carvers, and has been sent to Universal Exhibitions of recent years, it must be considered a possible effort for our great employers of skilled labour.
The panelling of wall surfaces will be divided into larger or smaller reticulations or framework, with some reference to the size of the room, that is to say, that very large and lofty rooms will not bear the smaller subdivision of space and delicate moulding lines which are so general in panelling of mediæval or very early Tudor houses, and which are in keeping on walls of moderate size. Any inlaying or variety of woods should be used on walls with great discretion.
So far, then, on the general consideration of the work, which it is the business of the furniture maker to produce. In theory, it is his object to satisfy daily wants and necessities in the most convenient, useful, and agreeable way.
The difference between rudeness and refinement in daily habits consists in putting first order and propriety, then comeliness and cheerfulness into our homes and habits. There is so much to be borne and to be done merely that we may live, so many contradictions to natural inclination meet us on all sides, that we look for repose, and some moderate satisfaction to the natural desire of the eye, in that which meets it, and must meet it, so constantly. This satisfaction is beauty, or some measure of it, or what we have grown to take for beauty. As the eye is more exercised, the mind more informed, and becomes a better monitor or corrective to the eye, so we get less satisfied with much that passes for beauty, and so, on the other hand, we find it out in objects in which it is commonly or often passed over.
A return prepared by the Commissioners for the Paris Exhibition, in 1867, gave the following as the number of manufacturers engaged in London in "the several branches of the fancy furniture trade."
|Carvers and gilders||342|
|Cabinet carvers, inlayers, and liners||108|
|Chair, sofa, and stool-makers||252|
Wood and cabinet wares were exported (in 1865) to the value of 289,887l., and imported to the value of 128,925l. 
The highest efforts of the trade are concentrated in a few large establishments in London and the great cities, which have their own cabinet makers, carvers, upholsterers, &c., on their premises. In some instances, one piece of furniture may pass through the hands of several branches of the manufacture. I may choose a few names of makers who presented their works in Paris in 1867 in alphabetical order, e.g. Messrs. Collinson and Locke, Crace, Dyer and Watts, Gillow, Herring, Holland, Howard, Hunter, Ingledew, Jackson and Graham, Morant, Trollope, Wertheimer, Wright and Mansfield. The larger of these establishments are supplied with steam machinery, and all the work that can possibly be executed by mechanical agency is prepared by these engines, leaving only the most costly operations to be executed by hand.
It is the province of the carpenter to put together simple woodwork; that which is an actual part of architecture, such as boxes, chests, benches, seats, shelves, and so forth as require only good material and neatness of hand in execution. The joiner and cabinet maker include this amount of skill as a foundation for their accomplishments, as a sculptor can block out a statue and a painter grind his colours, work, however, which in ordinary practice is handed over to assistants or apprentices.
Before discussing the materials and the methods of execution now in use, it would be well to notice a great change which has taken place both in the status of the workman, the division of labour, and the mechanical appliances now at his command.
Down to recent times, joinery and cabinet making were in the hands of a number of masters in the trade, far greater in comparison to the pressure of the demand on the part of buyers than is the case at present. We have a larger society of buyers, a greater demand for the execution of large orders at a rapid rate, than was the case in former generations. On the other hand, the trade is gathered up into fewer master hands. The masters then employed a less amount of labour. They took in apprentices, many of whom remained for years with them as assistants, and the establishment was more of a family. It followed, that all members of this smaller society worked together and took part in the particular sets of chairs, the tables, cabinets, and so forth, turned out from their own house. They were, moreover, animated in a closer and truer degree by the spirit, and adopted the ideas, of a master who worked with or overlooked and advised them constantly, than could be the case in our great modern establishments. Again, though, as I have already said, the old operations by which boards, bars, and other members of wood construction are joined together, have not substantially varied since the days of Egyptians and Romans, the methods of execution have undergone a great change, owing to the introduction of machinery. The skill and training of the hand of the workman must necessarily undergo a change as well, whether for the better or the worse. The workman is relieved from the necessity of attaining an absolute accuracy in much of the ordinary but essential work of joints, mortises and other operations which can be produced with an uniform exactness by mechanical means.
The fact, also, that different engines or lathes can produce at a prodigious rate certain separate parts of many pieces of furniture, has made skilled mechanics less universal "all round" men than they were. If this combination of qualities is to be met with in provincial towns or villages, there, without doubt, the standard of excellence is a lower one.
Materials and Execution.—The woods used for making furniture besides pines and deals, are birch and beech (used for stuffed chair-frames, couches, &c.) walnut, letter wood, Spanish and Honduras mahogany, sycamore, lime, pear, cherry of several kinds, and maple; ash, English, American, and Hungarian; oak, English, foreign, and pollard, with pieces cut from wens and sweet cedar. Turners use also plane, laburnum, yew, holly, and box. More precious woods are also used in furniture: rose-wood, satin-wood, ebony, and sandal-wood. Other rare woods are used in inlaying and marquetry.
Some of these materials, mahogany and walnut, which are much in use, are imported in vast logs, the former sometimes three feet square; when of very fine grain suited to veneers, worth 1000l. or more, per log.
The woods are stacked in yards, or, in London, where the space cannot otherwise be had, on platforms resting on the walls of the workshops, and fully exposed to the weather. Woods are dried after a year, or two years, according to the size of the log and nature of the wood. Oak is sometimes kept for eight or more years. When sawn into the scantlings required, it is further dried by placing the logs and planks in rooms heated by the waste steam from the engine. An American patented method of drying is to place a coil of pipes, through which exceedingly cold water is passed in the drying room, which condenses and carries off the vapours from the wood exposed to this heat. Some firms have tried this method, but, I believe, without much success.
Logs are cut up by the engine with three or more perpendicular saws at once, the teeth being set to the right and left alternately, to open a passage for the blades. More valuable woods, e.g. mahogany, are cut into thin plank by an horizontal saw. In this case the teeth are not bent, but a labourer opens the passage for the blade by lifting the plank with a wedge. As little waste of the material as possible is thus secured.
Further cutting up of the material is done by means of circular saws. Part of the saw rises through a metal table. A moveable bar is firmly screwed at one, two, or more inches from the blade, and the wood is pushed by the workman against the saw, keeping one surface against the fixed bar, so as to secure a straight cut of the thickness required. Most modern planing is done by a revolving cutter, brought to bear upon the wood, which is drawn under it on an iron table, with more or less pressure, according to the quantity to be taken off the surface. Messrs. Howard have contrived a tube with a blast down it, which carries the shavings at once to the furnace, otherwise the dust made by the flying particles of wood would be unendurable.
Mouldings for panelling, cornices, skirtings, &c., are cut by revolving cutters or chisels, filed to any desired shape and case-hardened. They are set in a perpendicular axle and cut horizontally, the wood being firmly pressed against the tool. The workman can gear the cutter or reverse the action, so as to make a neat finish to his work.
Formerly all such work was done with a plane, cut to the required figure, and the finishings of lines of moulding had to be carved with the hand.
Mortising is done by a revolving boring tool, against which the wood to be mortised is moved by a gradual action, from side to side, and backwards and forwards, till the exact depth and width are bored out; tenons fitting these cavities are cut in another lathe, also by mechanical action.
Turning lathes.—The legs of chairs and tables are made in lathes, the general outline being obtained by turning in the simple form. Portions of the legs are sometimes squared, and the square faces must be evenly graduated. These parts are cut as follows: the lathe and the leg in it are kept at rest, and a revolving tool—in fact, a small lathe with a perpendicular cutter in it, connected by a leather band with a spindle overhead—set in motion by the steam-engine. The workman passes this cutter carefully down the four surfaces of the portions to be squared, cutting to a given depth all down, but never losing the angle outlines originally found by the first turning. When flutings have to be cut down the legs, whether they are round or square, this is done by using a revolving cutter set with horizontal action, which passes carefully along at one level, and is geared by the joiner so as to graduate the width of each fluting, as it descends, if the diminishing size of the support or leg requires it.
Bars of chairs, edges of shelves, the stretchers (or connecting bars) under some kinds of tables, are cut into carved or other shapes by an endless band saw revolving on two rollers. The workman passes his wood along an iron table against the saw, gearing the former according to the pattern drawn on the surface.
Fretwork is done with a still finer hair or watch-spring saw, of which one end can be detached from the holder and passed through a small hole in the piece of wood where the piercing is to be cut out by the saw. This could not be done by an endless saw, which can only be used to shape out edges. The best saws of this description are made by Perin, in Paris.
Watch-spring saws strained in frames have long been in use. In the steam-engine it is the wood only that is moved, and as it rests on a steady table, it gives the workman a great advantage, and should enable him to shape out his design with a delicacy only attainable with greater difficulty by the old method.
The process of mitreing pieces of moulding, where they meet at an angle at a corner, is done by machinery in some houses. In the works of Messrs. Jackson and Graham, this is done by setting the pieces in a metal T square. They are carefully cut by hand, and as each piece is set in a frame geared to the angle required, and under the hand of an experienced workman, no inaccuracies are likely to occur. In cabinet-making and joinery of all kinds, the number of angles round which mouldings have to pass is very great, as anyone will see who is at the pains to notice the construction of furniture of the most ordinary kind. Any staring or opening of an oblique joint is destructive of the effect of such workmanship, as it is of the strength of the joint which is glued together, and requires absolute contact of the parts to be joined.
Much work, such as chair rails, table legs, balusters for little galleries or on a large scale, is turned and cut in the steam lathe by hand, using steam power only to turn it.
Joinery.—The pieces of wood thus prepared are made up in many different combinations. This is the work of the joiner. In the joiners' shop of Messrs. Jackson and Graham, for instance, several benches were shown to me occupied by lengths of wall-panelling in ebony, some of the work being intended to cover the wall of a staircase; it was therefore framed in sloping lines. Each panel was a rhomboid, and none of the sides or mouldings were at right angles to each other. The mouldings had several fine strings, ovaloes, &c., all specially designed by the architect of the house—as the fittings of well-furnished houses should be. For these, special cutters had been made and fitted to the steam-moulding machine. To show the back of the panelling, the workmen turned it over. Instead of each panel being held in a groove provided in the stiles and rails, a rebate only has been cut in the frame, and the panel fits into it from the back (as the stretcher of a picture fits into a picture-frame), while iron buttons screwed into the frame pieces hold the panels firmly in their places. The object of this is to allow for the contraction of the wood with the alterations of temperature. With some woods, however well seasoned, this provision is requisite, and it is the more necessary, when more than one material is employed. In using ebony over large surfaces, it is found that the lengths required for the continuous rails cannot be procured free from knots or faults; and particular kinds of wood (pear and other material) are stained and prepared, to supplement the ebony in these instances.
The joiners put together panelling, chairs, couches, frames of tables, shelves, cupboards, and other complex pieces of furniture.
Upholstery.—Chairs and sofas required to be stuffed are then handed over to the upholsterer, and the seats and backs are stuffed with curled horsehair, carefully arranged so as not to wear into holes. A French edge is given to some stuffed seats by bringing the edges of several ridges of horsehair together, so inclined towards the upper edge, that each roll receives support from the others, which react on the pressure thus brought upon them, like springs. One would suppose that these edges were maintained by whalebone, like the stocks in which a past stiff-necked generation suffered so much. Where ribbon scrolls, tiny bunches of flowers, &c., are carved on the frames and top rails of chairs and sofa-frames, if these are to be polished only, the polishing is done before the upholstery. If parts are to be gilt, or the whole gilt, these operations are postponed till the upholstery is completed. So also when panelling, sideboards, bookcases, &c., are to be made up, the moulded lines which can only be conveniently hand-polished while in lengths, are treated thus before making up; and there remain only flat panels and surfaces, that can be evenly rubbed for the final polishing. In upholstered furniture, the coverings would be greased and stained, if polishing were done over or in connection with them; but in the case of gilt work, it must be left in most cases to the last, for fear of dimming or rubbing the gold during the processes of sewing, nailing, stuffing, &c.
I may remark here, that though arm-chairs, fauteuils, &c., are made in great London establishments, the manufacture of light chairs on a large scale is a special branch of the trade, and mostly carried on at High Wycombe, in the neighbourhood of which town there are extensive woods of beech, and where land and water carriage is at hand to convey these productions to London and elsewhere.
Cabinet-making.—It is by no means easy to lay down the exact technical boundary between what I have been describing as joinery, and what I am now about to call cabinet-making. They are considered, however, as distinct branches or rather, perhaps, different operations of the trade; and in such establishments as we are discussing, the cabinet makers and joiners have their own separate workshops and benches, and corresponding separate repositories for storing and drying their woods. Every kind of work is required in making costly cabinets, bookcases, sideboards, commodes, or by whatever name we choose to call the beautiful chests, cupboards, and other artistic receptacles, tables, consoles, brackets, &c., that go to complete the requirements of our modern reception rooms.
They are seldom made with the quaint or elaborate interior fittings, such as have been alluded to in older work, but every resource is brought to bear on the external decoration. Here we come to the arts brought to bear on the ornamentation of furniture.
Let us begin with carving. Sculpture is the highest or most beautiful kind of decoration that can be applied to furniture. It can only be executed by a trained artist. To go no farther back here than the Italian and French Renaissance furniture, generally made of walnut-wood, it is the spirited and graceful sculpture that makes its first great attraction. The Italian carving of this kind is the most graceful; while that of France by Bachelier and others, and much that was executed in England and Germany, being, if less graceful, always spirited and thoroughly decorative. As a general rule, sculpture so applied is conventional in design and treatment, that is, we rarely see it, (except, perhaps, occasionally in little ivory statuettes, and in bas-reliefs,) strictly imitative of nature, like perfect Greek sculpture. But neither should we find strict studies from nature on Greek furniture, if we had it, except with the same limitations. The furniture made by Greco-Roman artists, and discovered at Pompeii,  bears witness to this assertion, such as a head, a bust, the claws of animals, sculptured on furniture generally ending in scrolls or leafwork. If a human figure is complete, it bears no real proportion to objects round it, and so on.
Excellent wood sculpture used to be executed in England, from the days of Grinling Gibbon to those of Adam and the Chippendales, suited to the furniture then in fashion. I wish I could say that our furniture makers of to-day could easily, or did generally, command such talents. Ingeniously carved representations of animals and game on sideboards we sometimes see, but game 'dead' in every sense. If, indeed, Messrs. Crace, Howard, Jackson and Graham, and other firms could persuade the Royal Academicians to model for them, those artists would have to give some material amount of time to the study of how they could so effectually modify their skill as to suit the requirements and opportunities of a piece of furniture, these being quite peculiar. The French are easily our masters in this respect, but even they sacrifice good qualities proper to this kind of sculpture, in a morbid search after the softness of nature.
A curious piece of mechanism has been invented, and is in use in most large London furniture workshops, for carving by steam. Besides boring out and cutting away superfluous material, there is an engine for making mechanical sculpture in bas-relief, or the round. The wood is fixed on a metal table, which is moved to and fro and up and down, so as to come in contact with a revolving cutter held above it. The wood is then shaped and cut, according as it is elevated or moved. There are three or four cutters, and one piece of wood may be placed under each. Under the middle cutter, replaced by a dummy tool that does not really cut, the workman places his cast or model, and makes the dummy cutter pass over every undulation of its surface. The two or three cutters on either side cut the corresponding blocks exactly to the same depths and undulations as are followed by the blunt tool. It is a copying machine. That such copies, though they may pass muster, will ever have the charm of original carving, the reader shall not be asked to believe.
Certain elaborate methods of decorating and finishing woodwork must now be described, viz. those known as inlaying and marquetry. These two processes are distinct, but marquetry furniture has often portions decorated with inlaying, as also carved ornaments and decorations of beaten, cast, or chiselled metal-work. This last addition is not generally of the same importance in our modern English woodwork that it was a century ago, and I will describe the former methods first.
Inlaying means the insertion of pieces of more costly wood, stone, small discs, or carved pieces of ivory, into a less valuable material. The process is as old as any manufacture in wood working of which we possess records. Beautiful plates or blocks of ivory can be seen in the Assyrian gallery of the British museum, found at Nineveh by Mr. Layard. They are deeply cut with lotus and other leaf decorations, figures and hieroglyphics, and most of them have an Egyptian character. The ivory figures, too, have been inlaid and filled up with vitrified material. Remains of these decorations are still discernible, and the thickness of many of these pieces of ivory shows that they have been sunk bodily into woodwork of a solid character.
No such work as this can be pointed out in our London workshops, but patterns and arabesques, both of wood and ivory, are occasionally let into solid beds of wood so deeply, as to be actually mortised into the main body of the structure. This is done both by our own makers and by the French cabinet maker, Henri Fourdinois, a prize piece of whose make was bought for the South Kensington museum. It is not uncommon to insert pieces of lapis lazuli, bloodstone, and precious marbles into centres of carved woodwork, and I may call attention to the use of plates, medallions and cameos of Wedgwood, or Sèvres ware, which were frequently inlaid by Chippendale, and by the great French furniture makers, or ébénistes, of the last century. These are used in the modern satin-wood furniture of Messrs. Wright and Mansfield, and I have lately seen a coarser material used, viz. bas-reliefs in stoneware, imitations of the gris de Flandres, by Messrs. Doulton. These last, however, may be said to be rather panels set in frames, than pieces let into cavities in wood.
Veneering and Marquetry.—An effective method of ornamenting woodwork by the application to the surface of other woods is what is known as veneering and marquetry. The surface is in both cases covered with a thin layer of other woods, fastened on with glue and by strong pressure. Some of the panelling, table tops, and other joiner's work already described, is clothed with a thin slice of more valuable wood. This is called veneering. Woods such as ebony, tuya, satin-wood, palm, hare-wood, and a number more, are only to be had in small scantlings, logs a few feet long, and six or seven inches wide. Other woods, of which the grain is most beautifully marked, are cut from roots, wens, and other excrescences of the trees, to which they belong, and are only found occasionally, and in lumps of no great size. The contortions of the grain, which make them so valuable and beautiful, are owing to peculiar conditions of growth. In all these cases an inch plank of wood has to be cut into very thin slices, twelve being cut with a saw, or from eighteen to twenty-two if it is cut with a knife, as in that case no material is wasted by the opening made by a saw. These slices are laid on the surface of well-seasoned wood, and in the workshops of our great manufacturers will be seen a metal table or bed, prepared expressly for the process of veneering.
Supposing the object to be veneered to be a large surface—a number of panels, or the top of a table of ebony, for instance—the substance of the table may be Honduras mahogany. The wood has been carefully seasoned, and the top grooved, tongued, and firmly glued up to the required form. The ebony surface is also carefully fitted together and glued on paper, the surface being left rough, so that the glue may have a firm hold on the fibre of the grain. A corresponding roughness is produced on the upper surface of the mahogany, which is then laid on the metal bed. Glue, perfectly fluid and hot, is now rapidly brushed over the entire surface, and the thin veneer top is laid upon it, and firmly pressed down by several workmen, who then carefully go over the whole with hammers having broad, flat heads; the object of this being to flatten any apparent thicknesses of glue or bubbles of air which would interfere with the perfect contact of the two surfaces of wood. The whole is then placed under a caul or frame that touches it all over, and a number of strong bars are screwed down till the greater part of the glue has been pressed out. The complete union of the surfaces of the woods is effected not so much by the quantity of glue as by the absolute exclusion of the air, and this can only be done by pressure. The whole metal bed or frame in which the veneering is performed is heated by steam, or by gas-burners, where steam cannot be applied. The wood is left for twenty-four or thirty hours, till the glue has been completely set and hardened. The caul or frame is then removed, the paper used to keep the thin veneer together before gluing is scraped off, and the work of finishing and French polishing takes place. French polish, or careful wax polish, has the effect of keeping out air and damp, which latter might soften the glue and disintegrate the surface veneer. It is to be observed, that such wood as the finest French or Italian walnut is often veneered on mahogany, for it lasts better in this condition than if it was solid; large surfaces and thicknesses of walnut being difficult to procure without faults. Walnut veneers are applied in greater thicknesses than ebony; and if the surfaces to which they are applied are curved, cauls, or shaped pieces of wood made to fit them, are screwed down and held by numerous wooden vices, as in the method already described.
Marquetry is the application of veneer made of different woods, ivory, &c., composed like a mosaic or painting executed in coloured woods. This kind of decoration is of ancient use, was much in vogue during the Renaissance of the fifteenth and sixteenth centuries, and was carried to a great pitch of perfection in France during the seventeenth and eighteenth. It is still practised, and the process may be seen in full activity in the workshops of our modern furniture makers. In cutting out the forms required for marquetry decoration, one, two, or more thicknesses of thin wood are gummed or pasted together, according to the pattern required. In many fine pieces of marquetry there are, as in the case of a cabinet or table, portions of the surface entirely occupied by quiet reticulated patterns. As in these cases the same pattern often recurs, several thicknesses of wood can be laid together, and are then firmly fixed in a vice, having pasted over them a piece of paper on which the pattern is drawn. A small hole is bored where it will not interfere with the design, and the end of a thin watch-spring saw is passed through, and then re-attached to the frame that strains it out in working order. With this in his hand, the workman carefully traces the outlines of his drawing, which the tenuity of the saw-blade allows the tool to follow into every curve and angle. The thicknesses are then separated with the blade of a knife, and the slices become alternately pattern and ground, so that a set of patterns and a set of matrices of each wood are ready for use, and can be applied either on different parts of the same, or on two separate pieces of furniture. If a flower or other ornament is required which will not be repeated, two thicknesses only will be cut together. It is necessary that the same action of the saw should cut out the pattern and the ground in the two woods required, so that they may fit exactly.
When all the portions of the design are cut out, they are pasted on paper, and can be fitted together like mosaic. A little sawdust from the woods used, and a very small quantity of glue, join the edges and fill up the fine openings made by the saw; and in this way the whole surface of the marquetry is laid down on paper. In the case of flowers, heads, architectural or other designs, some slight additions, either of lines to indicate stalks, leaf-fibre, or the features of the face, are made with a graver, and stained; or gradations of a brown colour are given, in the case of white or light-tinted wood, by partial burning. It was formerly the custom to burn with a hot iron, but a more delicate tint is given by using hot sand, and this is the best method of tinting beech, lime, holly, box, maple, or other woods which are nearly white. There remains nothing but to rough the surface of the furniture, and to lay down the marquetry on it, precisely as in the case of plain veneering. When the glue is dry and hard, the pressure is taken off, the paper which is on the outer surface is scraped away, and the whole rubbed down to a fine surface and French polished. The most beautiful work of this description was made in France by Riesener and David, during the reigns of Louis XV. and Louis XVI. Besides graceful and delicate design, which these artists (for such they were) thoroughly understood, the beauty of their work owes much to their charming feeling for colour. Both used light woods, such as maple, holly, box, lime, &c., and laid brown woods, such as laburnum and walnut, on this light ground. Sometimes architectural compositions in the manner of Pannini, a favourite Roman painter of the day, were designed over the doors or flaps of secrétaires and cabinets, or busts, medallions, baskets of roses, &c. The charm of the work is the grace and repose with which these simple decorations are laid on. Compare some of the work of Riesener and David, on the cabinet doors in the collection of Sir Richard Wallace, with the glaring contrasts, the gaudy, often discordant colouring, and the crowded compositions of modern marquetry, at least of most of it. There is a tenderness of treatment, a grace and harmony of colour and arrangement throughout the former, which is wholly wanting, and which no lapse of time will add to the latter. Though these criticisms are not meant to be applied to the products of the leading houses now under review, the reader who has taken an observant stroll amongst the furniture of Sir Richard Wallace, at Bethnal Green, will find abundant contrasts as he walks along the streets of London.
In order to illustrate my remarks on the processes of colouring woods by burning or etching, I may point to a large writing bureau, or secrétaire, belonging to Sir Richard Wallace, made by Riesener, in 1769 (and signed), for Stanislaus, king of Poland. It is decorated partly with reticulated pattern work, partly with the royal cipher in medallions, and with other medallions containing emblematic figures, such as a carrier pigeon, a cock, the emblem of vigilance, or the head of a girl placing her finger on her lips, an emblem of silence. All these medallion figures are broadly drawn, the very slightest and most delicate tint only being added to represent shading, while the drawing is a single line lightly pencilled.
The materials used in the best marquetry are lime, holly, box, maple, beech, poplar, for white; pear, laburnum, palm (cut across the grain), lignum vitæ, walnut, teak, partridge-wood, for brown; wood called in the trade fustic, satin-wood, for yellow; tulip, purple-wood, amboyna, mahogany, thuya, log-wood, cam-wood, and varieties of these woods, for red; ebony for black, or stained wood. Greens and blues are also stained with metallic dyes. The finest of the old work may be called studies in brown and white, and the red woods are used sparingly; the dyed woods still more so, nor can they be said ever to be really effective.
As an example of great mechanical skill in a modern piece of very difficult execution, I might call attention to Messrs. Jackson and Graham's elaborate cabinet of marquetry, in patterns of Oriental character, after designs by the late Mr. Owen Jones (sent to the Vienna Exhibition by Messrs. Jackson and Graham). It had an architectural front, with detached columns and groups of architectural mouldings, some of them put together with the lines of moulding in woods of contrasted hue, an element of ornamentation that took from the unity and completeness of cap or corona mouldings. The little columns of an inch and a half diameter were entirely covered with reticulated pattern in different woods. As the shafts were tapering, so the reticulated patterns had to be graduated in size from top to bottom. This was a feat of most difficult execution, nor was it the only difficulty in this portion of the design. The marquetry in the instance of these columns had to be wrapped round each circular shaft; and each edge, therefore, of every portion of pattern and groundwork had to be sawn out with bevelled edges, so that when rolled, the inner edges might meet and the outer edges remain in contact, which would not be so, were they not bevelled: the contrary would happen in that case, and the outer edges would start in sunder. These columns were two feet and some inches high, and the little reticulations of pattern recurred many dozens of times. The conditions of which I speak had to be carefully observed in the case of each. The pattern, too, was graduated, as above stated, so that they had to be sawn out by separate cuttings—a most laborious and costly operation.
We miss in the great English houses one of the most costly and beautiful elements in the adornment of furniture, and that is, the fine moulded and chiselled bronze work, always gilt, which enters so largely into the decoration of fine old French marquetry. The English furniture makers of a century ago were not so behindhand, and old carriages had door-handles, and furniture had mounts of gilt bronze. Probably the French were always superior to us in this kind of skill. They still produce good work of this class, cast and afterwards cleaned and tooled with the chisel, but it is not equal to the work of the same description by Gouthière, and the famous ciseleurs of Paris in the last century.
I must not pass over in silence a beautiful kind of furniture which was in fashion a century since, and has been revived by Messrs. Wright and Mansfield, and other firms, viz. satin-wood furniture. In the time of Chippendale, Sheraton, Lock, and other great cabinet makers, contemporaries of the French artists Riesener, Gouthière, and David, satin-wood was imported from India. It was made up by veneering, and was decorated with medallions, some of marquetry, some of Wedgwood ware, after the model of the French inlaying of Sèvres porcelain plaques, and in some instances painted with miniature scenes like the Vernis Martin, called after a French decorator of the name of Martin. Old examples of satin-wood furniture, such as tables, bookcases, chests of drawers, &c., are not uncommon, decorated in one or more of these methods. Cipriani and Angelica Kauffmann were employed amongst many others in painting cameo medallions, busts, Cupids and so forth for satin-wood furniture. Messrs. Wright and Mansfield have executed much of this work, and sent a cabinet of large size to the Paris Exhibition of 1867, decorated with medallions, swags, ribbons, &c., partly in marquetry of coloured woods, partly in plates of Wedgwood ware. The piece is further set off by carved and gilt portions, not, however, sufficiently attractive to add greatly to the effect of the whole cabinet, which is gay, cheerful, of beautiful hue, and excellent workmanship. It is in the South Kensington Museum.
Allusion has been made to the furniture of Boulle. It began to be made somewhere about 1660, and was perhaps the earliest start taken in the more modern manufacture of sumptuous furniture. I have already called it a great advance and improvement, rather than an absolutely new invention, for pieces are found of a date too early to have been the actual work of Boulle. When the tortoiseshell is dark and rich in hue, the brass of a good golden yellow, and the designs carefully drawn, Boulle work seems to equal in splendour, though not in preciousness, the gold and silver furniture of the ancients, and the inlaid work of agates, crystals, amethysts, &c., with mounts of ivory and silver made in Florence in the sixteenth century.
Boulle work is made occasionally by French and other foreign houses, and by Wertheimer of Bond street, but it is costly, and the rich relieved portions, such as the hinge and lock mounts, the salient medallions, masks, &c., set in central points of the composition, are either copies or imitations of old work. They lack the freshness, vigour, and spirit of the old French metallurgy.
A spurious kind of Boulle is made with a composition in place of the tortoiseshell.
Parquet floors are made by Messrs. Howard as follows: Slices of oak, varied sometimes with mahogany, walnut, and imitation ebony, are laid out and put together on a board. If rings, circles or other figures are introduced, these portions, patterns, and cavities as well as angular pieces are cut in the machine. The thickness of these pieces is a quarter of an inch. They are then laid on three thicknesses of pine, the grain of each thickness being laid crosswise to the one below, so as to keep the wood above from warping and opening. These are glued together, and kept for twenty-four hours under an hydraulic press. It is, in fact, coarse marquetry, and the whole is laid down over a rough deal floor. Messrs. Howard also glue up their quarter inch hardwoods without a pine backing, and lay them down with glue and fine brads on old deal floors, a less expensive method, and which can be adopted without raising the level of an old floor.
It is remarkable that English cabinet makers should so rarely make these floors, or architects lay them down in rooms of modern houses. The French, Germans of all states, Swiss, Belgians, in short most continental nations have these floors, and Swiss and Belgian flooring is imported into England. That of the Belgian joiners is in large pieces four feet or so square, of seasoned wood, moderate in price, and easily laid down.
In this country, our costly modern houses are barely provided with a border of a foot or so round the edges of the reception rooms. Even that is but an exceptional practice. Yet oak flooring is not a costly addition to important rooms, while the habit of keeping floors always covered with Brussels carpet tacked down is not the cleanest imaginable.
Another application of veneered wood practised by Messrs. Howard is called by them "wood tapestry." Very thin slices are arranged geometrically in large patterns, and fastened with glue on staircase and passage walls, or made into dado panelling to the room, in this case capped by mouldings.
An ingenious method of inlaying thin veneers on flat surfaces of wood by machinery has been patented by the same firm. Veneers or slices of wood about the thickness of coarse brown paper are glued on a board, e.g. a table top. A design punched out in zinc, of a thickness somewhat greater than that of the veneer, is laid over it, and the board is then placed under a heavy roller. The zinc is forced into the surface of the board by the roller to about the thickness of the veneer. A plane cleans off the rest of the veneer, leaving the portion only that answers to the zinc pattern, thus forced into the surface of the board. If soaked, the grain of the wood would push up the thin veneer, no doubt, but this is no greater risk than that to which all marquetry is exposed.
Neither of these inventions have as yet been carried beyond the simplest disposition of arrangement. What can be done in either method remains to be shown.
All the woodwork passed under review thus far in joinery and cabinet-work, is of hard woods. Much, however, of our modern furniture is of a less valuable description, and is made of pine, American birch, Hungarian and other ash. Pitch-pine, an exceedingly hard wood, difficult to dry, and with a disagreeable propensity to crack if not very well seasoned, is also used, and a beautiful material it is. Some small quantity of bedroom furniture in beech, oak, and ash is made in the workshops that I have been describing. As a general rule, however, this manufacture of soft woods is a separate branch of the trade. To see soft wood, such as pine, made up into admirable bedroom furniture, and French polished till the grain of it shows much of the delicacy and agreeableness of satin-wood, we should pay a visit to the works of Messrs. Dyer and Watts, in Islington, and to other houses that occupy their time exclusively in work of this kind. It is clean, cheerful, and, by comparison, cheap; is ornamented (in the works of Messrs. Dyer and Watts) with neat lines of red, grey, and black, some of the lines imitative of inlaid wood. It is popular, and if we proceed from the workshops of Messrs. Graham, Holland, and others, to their showrooms and warehouses, we shall find this deal furniture for sale, though they do not profess to make any of it. Less costly pine-wood furniture is painted green, or white, or in imitation of other woods.
The surface of woodwork, if the woods are valuable, is finished by French polishing. A solution of shell-lac is put on a rolled woollen rubber, which is then covered with a linen rag, on which the polisher puts a drop of linseed oil. He rubs this solution evenly over the entire surface of the wood as it passes through the fibre of the linen, smooth action being secured by the oil. It is laid on in successive fine coats till a glossy surface is obtained which is air and water-proof. For fine work the surface should not be so glossy as to look like japan work. French polishing preserves woods liable to split, such as oak, from the too rapid action of the air.
Graining is an imitation of oak or other woods. A light colour, chrome yellow, and white, is first laid on, and glazed over with brown. While still wet, the brown is combed with elastic square teethed combs to give the appearance of graining. Larger veins are wiped out by the thumb and a piece of rag. All sorts of woods are thus imitated, and the work when dry is varnished over. Independently of any skill or deceptiveness, this broken painted surface looks effective and lasts long.
Of the propriety of such a decoration there are many doubts, for the discussion of which there is not space here. Marble graining has long been represented in Italy, e.g. in the loggia of Raphael in the Vatican. But in that particular instance, the painting is a representation, not an imitation. Wood graining is performed in all countries, and such imitations seem to have been practised by the ancients.
Mr. Norman Shaw is now exhibiting in Exhibition road examples of woods with fine grain stained green, red, and other colours, and French polished, the grain showing as if the woods were naturally of those hues.
For inexhaustible resource in tinting, polishing, and decorating wood surfaces, we shall have to learn from the Japanese, from whom probably the famous Vernis Martin was first borrowed in the last century. Much imitation lac-japanning was executed in this country during the latter years of the century. This work is still made in Birmingham. Pieces of mother-o'-pearl are glued on wood and the intervening surface, covered with lac varnish which is rubbed smooth, coat after coat, with pumice and water, till the surface of the inlaid pearl shell is reached, and the whole ground to a glassy polish.
The number of hands employed in large cabinet-making and furnishing establishments is very considerable. Not only are the workshops well provided with joiners, cabinet makers, and turners, but also with upholsterers, cutters-out and workwomen, stuffing, tacking on or sewing on the covers of chairs, sofas, &c. Indeed, it is no uncommon occurrence for the entire furniture of royal palaces and yachts to be ordered from one of these firms by the courts of foreign potentates in every corner of the world. Chairs, tables, sideboards, &c., were made lately at Messrs. Holland's for a steam yacht of the Emperor of Austria; while Messrs. Jackson and Graham have been furnishing the palace of the Khedive at Grand Cairo.
To execute, with certainty and promptitude, orders such as these, both premises, plant (such as wood and machinery), and the command of first-rate hands, must be abundant. Painters, gilders, carpenters, paperers, and a miscellaneous assistant staff are required to pioneer the way for the more costly work, or to make all good behind it. The firm of Jackson and Graham, for instance, employs from 600 to 1000 hands, according to the time of the year or the pressure of orders; and pays out close upon 2000l. per week as wages, when all these hands are in full work; and to highly skilled craftsmen (independently of designers), occupied on the production of the most costly kind of furniture, 60l. to 230l. per week. The Howards employ from 150 to 200 hands on cabinet making and joinery alone. It is the variety and comprehensiveness of these operations, that is so profitable as a speculation. Such a business requires, it need hardly be said, a large capital, and must be liable to fluctuations.
The Past and the Future.
A few words must be given to a retrospect of the state of this branch of the national industry, and to its prospects. If we look back twenty-five years to the furniture exhibited in London in 1851, the improvement of the present time seems incredible.
We may take that Exhibition, the first of these modern displays of all sorts of products of labour, as a point of departure for our review.
In 1851, the Commissioners directed that a complete report should be drawn up on the subject of the decorative treatment of manufactures of all kinds, including the particular class of objects under discussion. The author of this report calls attention to what should be the first consideration, in the construction of objects for daily and personal use. From the continual presence of these things, "defects overlooked at first, or disregarded for some showy excellence, grow into great grievances, when, having become an offence, the annoyance daily increases. Here at least utility should be the first object, and as simplicity rarely offends, that ornament which is the most simple in style will be the most likely to give lasting satisfaction."  Yet on examining the furniture on the English side, the reporter could not but notice, how rarely this very obvious consideration had been attended to. "The ornament of such works on the English side consists largely of imitative carving." Ornaments consisting of flowers, garlands of massive size and absolute relief, were applied indiscriminately to bedsteads, sideboards, bookcases, pier-glasses, &c., without any principle of selection or accommodation. "The laws of ornament were as completely set aside as those of use and convenience. Many of these works, instead of being useful, would require a rail to keep off the household."
These strictures were far from being applicable to the entire British Exhibition of this class of work. One or two notable exceptions may be quoted, such as a bookcase carved in oak, exhibited by Mr. Crace, bought by the Commissioners and added to the Kensington collections. This and a few other works "are particularly to be commended for their sound constructive treatment, and for the very judicious manner in which ornament is made subservient to it. The metal-work is also excellent, and the brass fittings of the panels of the bookcase deserve to be studied, both for the manner in which they have been put together and for their graceful lines."
Four years later, in 1855, in the Paris Exhibition, our furniture and woodwork had made a stride forward, which was still more marked in the London Exhibition of 1862. By that time, our leading houses had appreciated the necessity of obtaining talented designers and foremen, and in many instances they had employed the first architects of the day to give them drawings. The result was a great progress. While the French, indeed, continued to produce very fine pieces, some on the best models, or rather after the principles of the best periods of the Renaissance, our own cabinet makers had run far on in the same direction and in many others, for the mediæval feeling had still a strong hold on the taste of English architects and their patrons.
The greatest change, however, was that which the Paris exhibition of 1867 brought to light. Fifteen full years had passed, since public attention had been called to any careful comparison between the state of our furniture and the decorations of the interiors of our houses, with those of other countries, and the advance was incalculably greater on the part of this country than on that of the other competing nations.
It is worth remarking, that in three great comparative Exhibitions, and particularly in that of 1867, national tastes and peculiarities seemed to have been so completely pared away, that it became difficult to keep the productions of the North and West of Europe from those of the South or the East, distinct in one's mind. Each nation followed the fashion of the works that had obtained the best prizes at former Exhibitions.
For the present, French Renaissance designs in woodwork, and the produce of the looms of Lyons in hangings, serve to give the key to the school of domestic and industrial art in this country. If we look at the richest and most costly productions that have been exhibited, and carried off prizes at the International Exhibitions of late years (and we have no other standard of easy comparison), it will be found that French cabinets, tables, and chairs have served as models to the successful competitors. Indeed, the most successful of such pieces of furniture are actually designed by French artists in some of our leading firms. There is a decided English type in the satin-wood furniture of Messrs. Wright and Mansfield, and there is some invention, though not always happy, about our designers of mediæval furniture. These productions are, however, too apt to be heavy and ecclesiastical, to follow rather the types of stone constructions, and the teachings of the admirable plates of Viollet-le-duc, than the lighter work, inaugurated, not without power and success, by Pugin. There is a company of artists, Morris and Co., who have combined painting and woodwork, and produced excellent results; but they have had few followers, or rather few successful followers. I cannot but mention with honourable commendation the Royal School of Art needlework, as a subsidiary branch of furniture art.
So far as to the past. With regard to the future some few remarks may not be out of place: on the excellence of workmanship, the propriety of design, and the beauty of decoration.
The altered conditions of a trade such as that of the cabinet maker, which combines the useful with the agreeable, comely, and beautiful, in its productions, have been alluded to already. This change must seriously affect the accomplishments of the workman. Instead of working under and with his master, he is become one of a regiment of officials. He cannot identify himself with the entire work of which he only executes members interchangeable with other members, all mechanically alike. Again, mortises, tenons, dovetails, and joinery of all sorts, no longer demand from hand-work the accuracy, neatness, and perfection of former days. These operations are done for him. Occasionally he supplements the work of the engine. Like a player who only plays music occasionally, we cannot expect him to retain all the fineness of his hand in perfection.
Is the modern workman, then, the equal of those of sixty years since, whose productions stand so well to this day, because of this perfection of manual dexterity? It will be difficult to maintain that he is, but it would be most unjust to deny either that the best workmanship can be turned out, or that it is turned out, of our great establishments. This is the work of the most choice and accomplished hands. In smaller London houses, and in the furniture which we find in the trade generally, the workmanship is inferior, relatively, to that of the former period.
The introduction of machinery, however, is a fact, and its effects on manual skill must be accepted as a necessity. Nor must we pass over the further fact, that if the modern joiner is not the equal of the journeymen of Chippendale, he can do more. He has powers at command, and can carry into execution quantities, beyond the reach of half-a-dozen, perhaps a score of his predecessors. The consumer ought to reap advantages from this latter fact which he has failed hitherto to get, as shall be explained presently.
This brings me to the consideration of the proprieties of design, and the beauty of decoration of our present furniture. If workmanship is affected by altered conditions of the manufacture, so also is design, that union of effective and suitable decoration with the required convenience of each piece of furniture, which may be called style.
The artist, as regards his productions or style, is fashioned partly by what he thinks and loves, partly by his materials and his tools. With some materials he can do little, for want of tools and appliances. As regards material, wood remains what it always has been, but the steam-engine supplies an absolutely new set of tools. What has been done with them? The impressed marquetry has been mentioned, but as yet nothing really new has been done by the use of machinery. Thin veneers which might be cut out with scissors, as if one were cutting paper in inexhaustible fulness and variety, are restricted, in this impressed marquetry, to such as can be copied in the coarse material, zinc, which has to be punched or sawn out for the manufacture. Then again we have the carving or copying machine. At present nothing more is done with it than to copy, and to copy somewhat clumsily, in duplicate or in large numbers, that which has first been carved or modelled by hand. It would be premature to decide, that with so powerful a tool in his hand, an accomplished artist trained to use it, could not produce real and rapid sculpture. But no such artist has yet stepped on the stage, and it can only be an artist who can put the matter to a proof.
In following the style and ornamentation of former periods, our new machinery is in no sense a help to us. The man who cuts out his material for a Sheraton chair felt what he was going to carve upon, chose his pieces, arranged the grain, and the spare material just as he would require it, with careful reference to the use of his carving tools from first to last. The pace, too, required in executing orders was then more deliberate; costly and elaborate plant and machinery not being required, provincial workmen of admirable skill were to be found in many towns. There is no royal process by which we can put a log of wood into one end of an engine, and find a chair, a table, or a cabinet at the other. What steam machinery does for us is to perform with certainty, and with immense rapidity, the simple operations of sawing, planing, boring, and turning. It is by turnery that ornamentation is done in the engine. Any length of moulded edges can be soon turned out, any amount of the parts of panelling, of turned rails, and of ornaments turned on flat surfaces pressed on the cutting tool, together with the piercing of fretwork and curved and shaped edges to boards. The saw being a fixture in this instance, is an advantage, but machine turnery is not rich in resources. The tool itself is filed laboriously to the mould required, and the wood merely pressed against it. When the wood revolves (as in the old lathe), the turner, with the simple edge of his chisel or his gouge, was the master of an endless variety of ornament limited only by his fancy or skill of hand.
It is nevertheless in the turnery and the fret-cutting machinery, that a furniture artist must find the elements of a style. The man of genius, the poet and maker, who can throw himself into these elements, will do wonders with them. The lathe is as old as history. During the sixteenth, seventeenth, and eighteenth centuries, turned wood furniture was made in considerable quantities in this country, in Italy, and in the Indian possessions of the Portuguese. All the furniture of Arabs, Moors, and Turks springs from the lathe and the moulding plane; the tables and stools, the ingenious reticulation of Cairene geometrical panelling, the screens of woodwork so effective in the queen of Arab cities and in Damascus are derived from these humble sources.
To surface ornament of marquetry, occasional carved insertions can be added. But light, neat, and elegant woodwork, panelling, bookcases, cabinets, dressers, chairs, and tables, can be turned out without these additions, and the variety might be endless.
Carved acanthus foliage, bulging legs and surfaces, artistic carving and marquetry, and chiselled metal-mountings must be the work of trained sculptors. The engine gives them no real help. To design, that is invent (not to copy), carving and marquetry that will bear comparison with the products of Riesener, and of the school of Gibbons, is not to be done by command of appliances or skilful workmanship only. The artist who is thoroughly at home in designs of this kind, is the pupil or descendant of masters whose traditions are well established:
"Fortes creantur fortibus."
But neat furniture, unornamented by hand-work, ought to be turned out of the engine-room, the perfection of lightness, convenience, and strength. And here the buyer will look for the advantage of cheapness. We do not find that our large makers supply well-made machine furniture cheap. As a broad rule, prices seem to be calculated on what a man would do, and work done in the machine is priced, as if a man had made it by hand. In point of fact, five or six men's work is done in the same time, and the cost of wages charged on articles so made, will leave a disproportioned profit, notwithstanding the expense of setting up and maintaining the steam plant.
Decorative furniture can never be had at a cheap rate.
A word, in conclusion, as to the arts which are necessarily pressed into the service of furniture, and their prospects of the future.
These "sumptuary" arts have been spoken of in these pages as a revival in furniture and style, as dead. The disorders that culminated in the French revolution cut off our present European thoughts, or at least our manners and customs, from the past.
We are now trying to revivify past traditions. The furniture makers have made extraordinary exertions in this direction. How will it be in the coming years?
Some critics are of opinion that "art manufacture" is a delusion, and that, if our academicians were equal to the ancient Greeks, we should not find that rich buyers would care about the shapes of their chairs (if comfortable), the colours of their walls, and so forth—a singular delusion. If Phidias, Michael Angelo, and Raphael exhibited at Burlington House, their pupils and followers would overflow with good work in various degrees of elaboration. We should find it in our churches, houses, seats, carriages, and the rest. This is what did happen when the great artists were flourishing. Ugliness and vulgarity were not endurable anywhere. Mentor expressed himself in drinking cups, Cellini in brooches, Holbein in daggers, Michael Angelo in a candlestick, Raphael culminated in a church banner. The art that finds its utterances on knobs, or handles, or drawer fronts, is restricted certainly, because the object is of awkward shape or surface, is to be handled and used, and is only a part of something larger. Nevertheless the street of tripods in Athens, the front of the biga in the Vatican, were "occasions" on which good sculptors did the best that those occasions allowed of. Four fine silver images, representing four great provincial capitals, in the Blacas Collection (now to be seen in the British Museum), were perhaps the ends of the poles of a Sedan chair.
Objects of this kind, though fragmentary, or slightly worked out, or combined in some grotesque but graceful fashion, with a piece of leaf or stalk, are the easy results of long years of mental and manual training.
The workman artist, therefore, though his productions may not be thought suitable for the Academy walls, is a child of the same school, as that which brings forth such portents as Phidias, Praxiteles, Michael Angelo, and Leonardo, not to speak of our Royal Academicians.
Artists who are "specialists," like Giovanni da Udine, will continue to do special things only, but those admirably. Where the arts flourish, there will be a large school that includes half a nation, artists of all ranges of education, refinement, and knowledge. Some will sculpture figures for the temple, others will be of the rank of workmen. Vasari has given full details of the sumptuous furniture which was executed by the sixteenth century Academicians of Florence.
How are we to procure such teachings? This was the question which Colbert put to himself in the reign of Louis XIV. He resolved it, by getting masters and teachers of every kind of sumptuary art from Italy. The result has been to give the French nation a lead in this kind of industry, that holds good even amidst the ruin of old traditions, at this day.
The Kensington schools, and those on the same pattern throughout the country, are efforts made by the Government to meet the wants of our manufacturers. They are inelastic, and it is too soon to judge of the work they are likely to do hereafter. The only great error in such education would be to train scholars to be "ornamentalists," i.e. to teach them conventional art.
Art is conventional in connection with architecture and furniture, because in most instances this is all that would be proper or look well. A good modeller, draughtsman, or carver, would become conventional just as occasion required, but with no abstract desire for ugliness or the grotesque. That artists should be generally well educated and good scholars, and that the profession should possess knowledge and refinement, is of more importance than most people suppose. This kind of refinement lay at the root of the universality of accomplishments of the sixteenth century artists.
Lastly, it is not enough that the profession only should be educated, so as to supply the manufacturer with designs. It is the rich that must be taught as well. We are neither Italians nor Frenchmen, and, indeed, speaking generally, we have not so much sense of beauty and propriety in art as those races have, even with such degeneracy as prevails but too widely over the Channel.
It is enough to look at modern London, to listen to the disputes of committees of management or selection for a public monument, a street, or a gallery, and to take a glance at their choice, to see what we are in these respects. But Englishmen are not wanting in genius, and in the matter of which these pages treat, they have played their part well in the past.
When buyers know what is ugly, they will not tolerate it about their houses; the eagerness to possess something new or original will give place to a just judgment of what is good, whether new or old. Most periods of good sumptuary art owe their designs to a few old types constantly reproduced under new and agreeable varieties, that are not radical changes. To know good from bad in these matters, is the result not of a natural instinct altogether, but of such a sense instructed by study, experience, and reflection. Nor, on the other hand, does such an instinct accompany great intellectual acquirements naturally, and as a matter of right. A man may possess a vast amount of learning, statesmanship, or professional knowledge, and be no judge of painting, sculpture, marquetry furniture, or blue porcelain. Nor, though he knows something of the history of these objects, will he necessarily admire and like the best or most beautiful examples. It is this sense of what is becoming, that has to be learned, though it is occasionally a natural gift. When whole nations have become used to good domestic art, public opinion will be sound, and will perpetuate itself as regards this subject matter, till some great national convulsion reduces sumptuous living, and refined social manners and habits, to ruin.
LONDON: PRINTED BY EDWARD STANFORD, 55, CHARING CROSS, S.W.
 These numbers are approximate translations of the numbers given in the communication: no object could be gained in giving complex fractions.
 1 ounce avoirdupois weighs 28·349 grammes.
 1 mètre equals 39·37 English inches.
 1 kilogramme = 2·2 lbs. avoirdupois.
 Cat. Brit. Section Exhibition, 1867, Introduction, p. 61.
 See also Q. de Quincy, Le Jupiter Olympien.
 Supplementary Report, chap. xxx.