a fine kind of earthen ware, chiefly manufactured in China, and thence called China-ware. All earthen wares which are white and semitransparent are generally called *porcelains*; but amongst these, so great differences may be observed, that notwithstanding the similarity of their external appearance, they cannot be considered as matters of the same kind. These differences are so evident, that even persons who are not connoisseurs in this way prefer much the porcelain of some countries to that of others.

The art of making porcelain is one of those in which Europe has been excelled by oriental nations. The first porcelain that was seen in Europe was brought from Japan and China. The whiteness, transparency, fineness, neatness, elegance, and even the magnificence of this pottery, which soon became the ornament of sumptuous tables, did not fail to excite the admiration Porcelain. ration and industry of Europeans; and their attempts have succeeded so well, that in different parts of Europe, earthen wares have been made so like the oriental that they have acquired the name of porcelain. The first European porcelains were made in Saxony and in France; and afterwards in England, Germany, and Italy; but as all these were different from the Japanese, so each of them had its peculiar character.

The illustrious Reaumur first attended to the manufacture of porcelain as a science, and communicated his researches in two memoirs before the Academy of Sciences in 1727 and 1729. He did not satisfy himself with considering the external appearance, the painting and gilding, which are only ornaments not essential to the porcelain, but he endeavoured to examine it internally; and having broken pieces of the Japanese, Saxon, and French porcelains, he examined the difference of their grains (which name is given to their internal structure). The grain of the Japanese porcelain appeared to him to be fine, close, compact, moderately smooth, and somewhat shining. The grain of the Saxon porcelain was found to be still more compact, not granulous, smooth, shining like enamel. Lastly, the porcelain of St Cloud had a grain much less close and fine than that of Japan; not, or but little, shining; and resembling the grain of sugar.

From these first observations Mr Reaumur perceived that porcelains differed considerably. That he might examine them further, he exposed them to a violent heat. More essential differences than those of the grain appeared upon this trial; for the Japanese porcelain was unaltered by the fire, and all the European were melted.

This essential difference betwixt the Japanese and European porcelains suggested to Mr Reaumur a very ingenious thought, and in many respects true, concerning the nature of porcelain in general. As all porcelains somewhat resemble glass in consistence and transparency, though they are less compact and much less transparent, Mr Reaumur considered them as semitransparent substances. But every substance may appear, and may actually be, in a semitransparent state in two ways: for, first, it may be entirely composed of vitrifiable or fusible matters; and in this case, by exposing it to the action of fire, it will be actually melted or vitrified, if the heat be sufficiently strong and long-continued. But as this change is not made instantly, especially when the heat is not very violent; and as it passes through different stages or degrees, which may be more easily observed as the heat is better managed; hence, by stopping in proper time the application of heat to porcelain made in this manner, we may obtain it in an intermediate state betwixt those of crude earths and of completely vitrified substances, and also possessed of the semitransparency and of the other sensible qualities of porcelain. We know also, that if such porcelain be exposed to a stronger degree of fire, it will then be completely fused and entirely vitrified. But the European porcelains tried by Mr Reaumur had this fusibility; from which he concluded, that their composition is founded upon the abovementioned principle.

In the second place, a paste of porcelain may be composed of fusible and vitrifiable matter, mixed with a certain proportion of another matter which is absolutely unfusible in the fires of our furnaces. We may easily perceive, that if such a mixture be exposed to a heat sufficient to melt entirely the vitrifiable ingredient, that this matter will actually melt; but as it is intermixed with another matter which does not melt, and which consequently preserves its consistence and opacity, the whole must form a compound partly opake and partly transparent; or rather a semitransparent mass; that is, a semi-vitrified substance, or porcelain, but of a kind very different from the former; for as the fusible part of this latter has produced all its effect, and as it has been as much fused as it can be during the baking of the porcelain, the compound may be exposed a second time to a more violent fire, without approaching nearer to a complete vitrification, or without departing from its state of porcelain. But as oriental porcelain has precisely these appearances and properties, Mr Reaumur concludes with reason, that it is composed upon this principle; and he afterwards confirmed his opinion by undeniable facts.

Father Entrecelles, missionary at China, had sent from thence a summary description of the process by which the inhabitants of that country make their porcelain, and also a small quantity of the materials which they employ in its composition. He said that the Chinese composed their porcelain of two ingredients; one of which is a hard stone or rock, called by them petunse, which they carefully grind to a very fine powder; and the other, called by them kaolin, is a white, earthy substance, which they mix intimately with the ground petunse. Mr Reaumur examined both these matters, and having exposed them separately to a violent fire, he discovered that the petunse had fused without addition, and that the kaolin had given no sign of fusibility. He afterwards mixed these matters, and formed cakes of them, which by baking were converted into porcelain similar to that of China. Mr Reaumur easily found, that the petunse of the Chinese was a hard stone of the kind called vitrifiable, but much more fusible than any of those which were known in Europe; and that the kaolin was a talc matter, reduced to a very fine powder. From that time he hoped to make a porcelain of the same kind as the Chinese with materials found in France. Whether he could not find any materials equal to those of China, particularly that material analogous to the petunse of the Chinese, or because other occupations prevented the continuance of his researches, we do not know; but we find, from his second memoir upon porcelain, that he afterwards attempted to make an artificial petunse, by mixing our vitrifiable stones with salts capable of rendering them fusible, or even by substituting for it glass ready formed, and by adding to these such substances as he thought might be substituted for kaolin. But he probably found he could not execute these intentions; for he did not resume this subject from the year 1729 to 1739, when he gave a method for converting common glass to a singular kind of porcelain, to which he has given his name, and of which an account is given under the article Chemistry, n° 92.

Although Mr Reaumur has surmounted many difficulties, and has given just notions concerning this subject, yet he has been mistaken, or rather misled, in particular two important points. His first error concerns the Saxon Porcelain. Saxon porcelain, which he confounds with the other fusible porcelains made in Europe. Formerly, indeed, a porcelain might be made in Saxony, composed entirely of fusible or vitrifiable materials, the vitrification of which was stopped in proper time, and which Mr. Reaumur had examined. But now we are certainly informed, that all of that country is capable of resisting the most violent fires without fusion, as well, at least, as those of China and Japan. Mr. Reaumur might have been misled by the appearance of the internal texture of this porcelain. For when a piece of it is broken, its internal surface does not appear granulous, but compact, uniform, smooth, shining, and much resembling white enamel. But this appearance, so far from showing that Saxon porcelain is a fused or vitrified substance, proves that it is not entirely composed of fusible matters. All who have considered attentively this subject know, that the internal surface of the most fusible porcelains is also the least dense and least compact; the reason of which is, that no vitreous matter can be smooth and dense internally, unless it has been completely fused. But if the density and shining appearance of the internal surface of the Saxon porcelain were only the effects of the fusion of a vitreous matter, how could we conceive that vessels formed of that matter should have sustained the necessary fusion for giving this density and shining appearance, without having entirely lost their shape? The impossibility of this is evident to any persons who have been conversant in these matters and in the fusion of glass.

This quality of the Saxon porcelain must therefore, between the proceed from another cause. It does indeed contain, as every porcelain does, particularly those of China and Japan, a fusible substance, which has been even completely fused during the baking. Its density also and its internal lustre proceed chiefly from this fused matter; but we are also certain, that it contains a large quantity of a substance absolutely unfusible, from which it receives its admirable whiteness, its firmness and solidity, during the baking; in a word, which supplies the place of the oriental kaolin, and which has the property of contracting its dimensions considerably while it incorporates with the fusible substance. If it be subjected to the most decisive trial, namely, the action of a violent fire, capable of melting every porcelain composed of fusible matters alone, "I affirm," says Mr. Macquer, "after many experiments, that it cannot be fused, unless by a fire capable also of melting the best Japanese porcelain." The Saxon porcelain is therefore not to be confounded with those which are vitreous and fusible; but is in its kind as excellent as that of Japan, and perhaps superior, as we shall see when we enumerate the qualities which constitute the excellence of porcelain. The subject of Mr. Reaumur's second error, or at least that which he has not sufficiently explained, is the kaolin of China. According to him, this matter is a fine talc powder, from the mixture of which with petuntse the oriental porcelain is formed. Possibly a very finely-ground talc substance mixed with petuntse might form a porcelain similar to the oriental; but persons acquainted with the manufacture of any porcelain, must perceive the impossibility of forming vessels, unless the paste of which they are made be so ductile and tenacious, that it may be worked upon a potter's lathe, or at least that it may be moulded. But talc, porcelain, or any kinds of stones, however finely-ground, cannot acquire the requisite tenacity, which clays only, of all known earthly substances, possess. The Chinese porcelain vessels evidently appear to be turned upon the lathe, since they retain the marks of it; hence they must have been formed of a very tenacious paste, and consequently the kaolin is not a purely talc matter, but is mixed with clay; or else the petuntse and kaolin are not, as Mr. Reaumur supposes, the only ingredients of the paste of which Chinese porcelain is formed, but a sufficient quantity of some binding matter, unknown to father d'Entrecollès and Mr. Reaumur, must be also added.

Although, since Mr. Reaumur, no scientific person has written concerning porcelain, many have attempted to make it. Manufactories have been established in almost all the states of Europe. Besides that of Saxony, which has been long established, porcelain is also made at Vienna, at Frankendal, and lately in the neighbourhood of Berlin. All these German porcelains are similar to the Saxon; and are made of materials of the same kind, although they differ somewhat from each other. England and Italy also have their porcelains, the chief of which are those of Chelsea and of Naples. Mr. de la Condamine, in his last journey into Italy, visited a manufacture of porcelain established at Florence by the marquis de la Ginori, then governor of Leghorn. Mr. de la Condamine observed particularly the large size of some pieces of this porcelain. He says he saw statues and groups half as large as nature, modelled from some of the finest antiques. The furnaces in which the porcelain was baked were constructed with much art, and lined with bricks made of the porcelain materials. The paste of this porcelain is very beautiful; and from the grain of broken pieces it, appears to have all the qualities of the best Chinese porcelain. A whiter glazing would be desirable, which they might probably attain, if the Marquis Ginori was not determined to use those materials only which were found in that country.

But in no state of Europe have such attempts been made to discover porcelain, or so many manufactories of it been established, as in France. Before even Mr. Reaumur had published on this subject, porcelain was made at Saint Cloud, and in the suburb of St. Antoine at Paris, which was of the vitreous and fusible kind, but considerably beautiful. Since that time, considerable manufactures of it have been established at Chantilly, at Villeroi, and at Orleans; the porcelains of which have a distinguished merit. But the porcelain produced in the king's manufacture at Sevres holds at present the first rank, from its shining white, its beautiful glazing, and coloured grounds, in which no porcelain has ever equalled it. The magnificence of the gilding, the regularity and elegance of its forms, surpass every thing of the kind.

Mr. Guettard has published an account of his discoveries on this subject, in the Memoirs of the Academy of Sciences for the year 1765. The kaolin which he employed was a white argillaceous earth, filled with mica, which he found in the neighbourhood of Alençon; and his petuntse is a hard, quartzose grit stone, found abundantly in the same country, with which the streets of Alençon are paved. We al- Porcelain so know that Mr Guettard had begun to make his experiments on porcelain with these materials in the year 1751, together with the late Duke of Orleans, to whom he was attached. The Count de Lauraguais, of the Academy of Sciences, engaged in the pursuit of porcelain for several years with uncommon ardour and constancy. He spared no trouble nor expense to attain his purpose, which was to make porcelain equal in all respects to that of China and Japan. He showed some pieces made by him, in the year 1766, to the members of the Academy of Sciences. The persons appointed by them to examine it gave their opinion, "that of all the porcelains made in the country, that of the Count de Lauraguais most resembles the porcelain of China and Japan in solidity, grain, and unfusibility." It were to be wished that it possessed equally the other qualities essential to the excellence of porcelain, namely, the whiteness and lustre observable in the ancient Japanese porcelain. See Chemistry, p. 91.

We shall now show what those qualities are which constitute the perfection of porcelain. We must first carefully distinguish the qualities which only contribute to the beauty and external appearance, from the intrinsic and essential properties in which the goodness and solidity of porcelain consist. All persons who have made experiments in this way have soon discovered the possibility of making compounds very white, beautifully semi-transparent, and covered with a thin glazing; but which cannot be worked for want of tenacity, are not sufficiently compact, are essentially fusible, are subject to break by sudden application of heat and cold; and lastly, the glazing of which cracks, becomes rough, and consequently loses its lustre by use, because it is too soft.

On the other side, we shall also find it not difficult to compose very tenacious pastes, which shall be capable of being easily worked and well baked; which in the baking shall acquire the desirable hardness and density; which are unfusible, and capable of sustaining very well the sudden change of heat and cold; and, in a word, which shall have all the qualities of the most excellent porcelain, excepting whiteness and beauty. We shall soon see that the materials fit for the composition of such porcelains may be found abundantly in every country. The only difficulty, then, in this inquiry concerning porcelain, is, to unite beauty and goodness in one composition; and indeed nature seems to be very sparing of materials fit for this purpose, and therefore perfect porcelain will always be a dear and valuable commodity.

Those potteries which we call stone-ware are not of modern invention, and have all the essential qualities of the best Japanese. For if we except whiteness, on which alone the semi-transparency depends, and compare all the properties of Japanese porcelain with those of our stone-ware, no difference can be found between them. The same grain appears internally in both; the same sound is produced by striking them when properly suspended; the same density, the same hardness by which they strike fire with steel, the same faculty of sustaining the heat of boiling liquors without breaking, and the same unfusibility in fire, are observable. Lastly, if the earths of which stone-ware is made were free from heterogeneous colouring matters, which prevent their whiteness and semitransparency; if vessels were carefully formed; if all the proper attentions were given; and if these vessels were covered over with a fine glazing; they would be as perfect porcelain as that of Japan. The most perfect porcelains, therefore, is nothing else than a fine white stone-ware.

Earths of this kind are probably more rare in Europe than in Japan and China. And probably also the want of these earths was the cause that the first makers of porcelain in this country confined themselves to an external imitation, by employing nothing but vitrifiable matters with fusible salts and a small quantity of white earth, from which fusible and vitreous porcelains were composed, which might be called false porcelains. But things are much changed since their first attempts. Besides the discoveries of the count de Lauraguais and genius of Mr Guettard, genuine white porcelains have been made a long time ago in Germany, especially in Saxony and at Frankendal.

These porcelains are not inferior in any respect to rope, the oriental; they are even much superior in beauty and whiteness to the modern oriental porcelain, which has much degenerated in these respects; they seem even to excel the oriental in the most valuable quality of porcelain, namely, the property of sustaining the sudden change of heat and cold. We cannot judge of the quality of porcelain by a flight trial; for so many circumstances concur to make a piece of porcelain capable or incapable of sustaining the sudden application of heat and of cold, that if at the same time boiling water be poured into two vessels, one of which is good porcelain and the other bad, the former may possibly break and the latter remain entire. The only true method of discovering good porcelain in this respect is, to examine several pieces of it which are daily used; for instance, a set of coffee-cups. But it has been observed, that in many such pieces of oriental porcelain, which have been long and daily used, cracks in the direction of their height may be always perceived, which are never seen in the good European porcelains.

Every one talks of porcelain, and yet few are connoisseurs of it. None can be considered as such but those who have long made it an object of their inquiries. That the ancient Japanese porcelain is the most perfect, is a general opinion. This porcelain is indeed very beautiful, and we must also acknowledge that its quality is excellent. It has been our model, and has long been the object of our admiration and emulation; but which we have been never able to equal, and which many persons believe never can be equalled. Some persons even deify the Saxon porcelain for a quality which really gives it a superiority to the Japanese, namely, the greater smoothness, lustre, and less granulous appearance of its internal surface than the oriental. The resemblance of this surface to that of glass has evidently suggested this notion: and it would be well founded, if the density and lustre of this porcelain proceeded only from a fusible and vitreous quality; but as they do not, and as this porcelain is as fixed and as unfusible as the Japanese, its density, far from being a fault, is a valuable quality. For we must allow, that of porcelains equal in other respects, those are best which are most firm and compact. Hence the interior substance of the Japanese porcelain is esteemed for its great- Porcelain, or density, compactness, and lustre, than our vitreous sand or frit porcelain, because these qualities indicate greater cohesion, and more intimate incorporation of its parts. For the same reason also the superior density of the Saxon porcelain ought to give it the preference to the Japanese. Besides, nothing would be easier than to give the Saxon porcelain the granular texture of the Japanese, by mixing with the paste a certain quantity of sand. But the persons who perfected that manufacture were certainly sensible, that such a conformity to the Japanese porcelain would lessen the merit of theirs. For we know, that in general porcelains are better in proportion as they contain a larger proportion of clay or earth, and less of sand, flints, or other matters of that kind.

What we have said concerning porcelain in general, and the principal kinds of it, seems sufficient to give just notions of it, if not to persons who without considering the subject are determined to prefer the most ancient, to those, at least, who have made experiments on this subject; or who, having a sufficient knowledge of chemistry, are capable of studying and examining it thoroughly. We shall finish this article by giving a short description of the method of manufacturing porcelain.

The basis of the porcelains which we have called fusible, vitreous, or false porcelains, is called by artists a frit; which is nothing else than a mixture of sand or powdered flints, with salts capable of dissolving them to fusion, and of giving them a great whiteness by means of a sufficient heat. This frit is to be then mixed with as much, and no more, of a white tenacious earth of an argillaceous or marly nature, than is sufficient to make it capable of being worked upon the wheel. The whole mixture is to be well ground together in a mill, and made into a paste, which is to be formed, either upon the wheel or in moulds, into pieces of such forms as are required.

Each of these pieces, when dry, is to be put into a case made of earthen ware (a); which cases are to be ranged in piles one upon another, in a furnace or kiln, which is to be filled with these to the roof. The furnaces are chambers or cavities of various forms and sizes; and are so disposed, that their fire-place is placed on the outside opposite to one or more openings, which communicate within the furnace. The flame of the fuel is drawn within the furnace, the air of which rarifying, determines a current of air from without inwards, as in all furnaces. At first a very little fire is made, that the furnace may be heated gradually, and is to be increased more and more till the porcelain is baked, that is, till it has acquired its proper hardness and transparency; which is known by taking out of the furnace from time to time, and examining, small pieces of porcelain, placed for that purpose in cases which have lateral openings. When these pieces show that the porcelain is sufficiently baked, the fire is no longer to be supplied with fuel, the furnace is to be cooled, and the porcelain taken out, which in this state resembles white marble not having a shining surface, which is afterwards to be given by covering them with a vitreous composition called the glazing.

The porcelain when baked and not glazed is called biscuit, which is more or less beautiful according to the porcelain nature of the porcelain. The manufacture of Sévres sculptures excels all others in this respect, and it is therefore the only one which can produce very fine pieces of sculpture; that is, in which all the fineness of the workmanship is preserved, and which are preferable in smoothness and whiteness to the finest marble of Italy.

As no piece of sculpture of this kind can preserve all the delicacy of its workmanship when covered with a glazing; and as sculptors avoid polishing their marble figures, because the lustre of the polish is disadvantageous; therefore, in the manufactures at Sévres, all figures, or little statues, and even some ornamental vases, are left in the state of biscuit. The other pieces of porcelain are to be glazed in the following manner.

A glaze is first to be composed suited to the nature of the porcelain to which it is to be applied; for every glazing and glaze is not fit for this purpose. We frequently find colours that a glaze which makes a fine glazing for one porcelain shall make a very bad glazing for another porcelain; shall crack in many places, shall have no lustre, or shall contain bubbles. The glazing then must be appropriated to each porcelain, that is, to the hardness and density of the ware, and to the ingredients of its composition, &c.

These glazings are prepared by previously fusing together all the substances of which they consist, so as to form vitreous masses. These masses are to be ground very finely in a mill. This vitreous powder is to be mixed with a sufficient quantity of water, or other proper liquor, so that the mixture shall have the consistence of cream of milk. The pieces of porcelain are to be covered with a thin stratum of this matter; and when very dry, they are to be again put into the furnace in the same manner as before for the forming of the biscuit, and to be continued there till the glazing be well fused. The necessary degree of fire for fusing the glazing is much less than that for baking the paste.

The pieces of porcelain which are intended to remain white are now finished; but those which are to be painted and gilded must undergo further operations. The colours to be applied are the same as those used for enamel painting. They all consist of metallic calxes bruised and incorporated with a very fusible glaze. Crocus of iron furnishes a red colour; Gold + precipitated by tin makes the purple and violet; copper calcined by acids and precipitated by an alkali gives a fine green; zaffire makes the blue; earths slightly ferruginous produce a yellow; and, lastly, brown and black colours are produced by calcined iron, together with a deep blue of zaffire. These colours being ground with gum-water, or with oil of spike, are to be employed for the painting of the porcelain with designs of flowers and other figures. For gilding, a powder or calx of gold is to be applied in the same manner as the coloured enamels. The painted and gilded porcelains are to be then exposed to a fire capable of fusing the glaze, with which the metallic colours are mixed.

Thus

(a) The cases are called by English potters, seggers. They are generally formed of coarser clays, but which must be also capable of sustaining the heat required without fusion. By means of these cases, the contained porcelain is preserved from the smoke of the burning fuel. The whiteness of the porcelain depends much on their compactness of texture by which the smoke is excluded, and on the purity of the clay of which they are made. Thus the colours are made to adhere, and at the same time acquire a gloss equal to that of the glazing. The gold alone has not then a shining appearance, which must be afterwards given to it by burnishing with a blood stone.

The operations for the unsuitable porcelains, and also for such as are of the nature of stone-ware, are somewhat more simple. The sands and stones which enter into their composition are to be ground in a mill; the earths or clays are to be washed: the materials are to be well mixed, and formed into a paste; the pieces are first rudely formed upon a potter's wheel; and when dry, or half dry, they are turned again upon the wheel, and their form is made more perfect; they are then placed in the furnace, not to bake them, but only to apply a sufficient heat to give them such a solidity that they may be handled without breaking, and may receive the glazing. As the pieces of porcelain after this flight heat are very dry, they imbibe water readily. This disposition affords the application of the glazing. The vitrifiable or vitrified matter of this glazing, which has been previously ground in a mill, is to be mixed with such a quantity of water, that the liquor shall have the consistence of milk. The pieces of porcelain are hastily dipped in this liquor, the water of which they imbibe, and thus on their surface is left an uniform covering of the glazing materials. This covering, which ought to be very thin, will soon become too dry, that it cannot stick to the fingers when the pieces are handled.

The pieces of this porcelain are then put into the furnace to be perfectly baked. The heat is to be raised to such a height, that all within the furnace shall be white, and the cases shall be undistinguishable from the flame. When, by taking out small pieces, the porcelain is known to be sufficiently baked, the fire is discontinued, and the furnace cooled. If the baking has been well performed, the pieces of porcelain will be found by this single operation to be rendered compact, sonorous, close-grained, moderately glossy, and covered externally with a fine glazing. The painting and gilding of this porcelain are to be executed in a manner similar to that already described.

Porcelain Shell, a species of Cypraea.