Porcelain. red-hot, and if the colours of the porcelain appear with full luftre, he judges that it is in a proper ftate; he then difcontinues the fire, and entirely clofes up the mouth of the furnace for fome time. In the bottom of the furnace there is a deep hearth about. two feet in breadth, over which a plank is laid, in order that the workman may enter to arrange the porcelain. When the fire is kindled on this hearth, the mouth of the furnace is immediately clofed up, and an aperture is left only fufficient for the admiffion of faggots about a foot in length, but very narrow. The furnace is first heated for a day and night; after which two men keep continually throwing wood into it, and relieve each other by turns: 180 loads are generally confumed for one baking. As the porcelain is burning hot, the workman employs for the purpose of taking it out long scarfs or pieces of cloth, which are fufpended from his neck." 18 Their dif ferent ciaf celain. The Chinese divide their porcelain into feveral claffes, fes of por according to its different degrees of fineness and beauty. The whole of the firft is referved for the emperor. None of thefe works ever come into the hands of the public, unless they have blemishes or imperfections which render them unworthy of being prefented to the fovereign. It is much to be doubted whether any of the largeft and fineft porcelain of China has ever been brought to Europe; the miffionaries at least affure us that none of that kind is fold at Canton. The Chinese fet fome value upon the Drefden porcelain, and ftill more upon that which comes from the manufactories of France. 19 Porcelain first examined fcien Reaumur The illuftrious Reaumur first attended to the manu facture of porcelain as a science, and communicated his tifically by researches in two memoirs before the Academy of Sciences in 1727 and 1729. He did not fatisfy himself with confidering the external appearance, the painting and gilding, which are only ornaments not effential to the porcelain, but he endeavoured to examine it internally; and having broken pieces of the Japanefe, Sax on, and French porcelains, he examined the difference of their grains (which name is given to their internal ftructure). The grain of the Japanese porcelain appeared to him to be fine, clofe, compact, moderately fmooth, and fomewhat fhining. The grain of the Sax. on porcelain was found to be ftill more compact, not Different granulous, fmooth, fhining like enamel. Laftly, the kinds of it. porcelain of St Cloud had a grain much lefs clofe and fine than that of Japan; not, or but little, fhining; and resembling the grain of fugar. 20 21. s true. From thefe firft obfervations Mr Reaumur perceived that porcelains differed confiderably. That he might examine them further, he expofed them to a violent heat. More effential differences than those of the grain appeared upon this trial; for the Japanese porcelain was unalterable by the fire, and all the European were melted. This effential difference betwixt the Japanese and European porcelains fuggefted to Mr Reaumur a very ingenious thought, and in many respects true, concerning the nature of porcelain in general. As all porcecompofition difco- lains fomewhat refemble glafs in confiftence and tranfvered by parency, though they are lefs compact and much lefs Reaumur, tranfparent, Mr Reaumur confidered them as femivitrifications. But every fubitance may appear, and may actually be, in a femivitrified ftate in two ways: for, first, it may be entirely compofed of vitrifiable or fufible Porcelain. matters; and in this cafe, by expofing it to the action of fire, it will be actually melted or vitrified, if the heat be fufficiently strong and long continued. But as this change is not made inftantly, especially when the heat is not very violent; and as it paffes through different ftages 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 thofe of crude earths and of completely vitrified fubftances, and alfo poffeffed of the femitranfparency and of the other fenfible qualities of porcelain. We know alfo, that if fuch porcelain be expofed to a stronger degree of heat, it will then be completely fufed and entirely vitrified. But the European porcelains tried by Mr Reaumur had this fufibility; from which he concluded, that their compofition is founded upon the above-mentioned principle. In the fecond place, a paste of porcelain may be com pofed of fufible and vitrifiable matter, mixed with a.. certain proportion of another matter which is abfolutely unfufible in the fires of our furnaces. We may ea-fily perceive, that if fuch a mixture be expofed to a heat fufficient 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 confequently preferves its confiftency and opacity, the whole muft form a compound partly opaque and partly transparent, or rather a femitransparent mafs; that is, a femivitrified fubftance or porcelain, but of a kind very different from the former; for as the fufible part of this latter has produced all its effect, and as it has been as much fufed as it can be during the baking of the porcelain, the compound may be expofed a fecond time to a more violent fire, without approaching nearer to a complete vitrification, or without departing from its ftate of porcelain. But as oriental porcelain has precisely thefe appearances and properties, Mr Reaumur concludes with reason, that it is compofed upon this principle; and he afterwards confirmed his opinion by undeniable facts. Mr Reaumur examined the pe-tun-tse and kao-lin of the Chinese, and having exposed them separately to a violent fire, he discovered that the pe-tun-tse had fufed without addition, and that the kao-lin had given no fign of fufibility. He afterwards mixed these matters, and formed cakes of them, which by baking were converted into porcelain fimilar to that of China. Mr Reaumur eafily found, that the pe-tun-tfe of the Chinefe was a hard stone of the kind called vitrifiable, but much more fufible than any of those which were known in Europe; and that the kao-lin was a talky matter, reduced to a very fine powder. From that time he hoped to make a porcelain of the fame kind as the Chinese with materials found in France. Whether he could not find any materials equal to thofe of China, particu larly that material analogous to the pe-tun-tfe of the Chinese, or because other occupations prevented the continuance of his researches, we do not know; but we find, from his fecond memoir upon porcelain, that he afterwards attempted to make an artificial pe-tun-tse, by mixing our vitrifiable ftones with falts capable of rendering them fufible, or even by fubftituting for it glass ready formed, and by adding to thefe fuch fub Kances 22 POR Porcelain Aanees as he thought might be fubftituted for kao-lin. 23 He is miftaken in fome Although Mr Reaumur has furmounted many difficulties, and has given just notions concerning this fubticulars.ject, yet he has been mistaken, or rather mifled, in two important points. His firft error concerns the Saxon porcelain, which he confounds with the other fufible porcelains made in Europe. Formerly, indeed, a porcelain might be made in Saxony, compofed entirely of fufible or vitrifiable materials, the vitrification of which was ftopt in proper time, and which Mr Reaumur had examined. But now we are certainly informed, that all of that country is capable of refifting the most violent fires without fufion, as well at least as those of China and Japan. Mr Reaumur might have been mifled by the appearance of the internal texture of this porcelain. For when a piece of it is broken, its internal furface does not appear granulous, but compact, uniform, fmooth, fhining, and much refembling white enamel. But this appearance, so far from showing that Saxon porcelain is a fufed or vitrified fubftance, proves that it is not entirely compofed of fufible matters. who have confidered attentively this fubject know, that All the internal furface of the most fufible porcelains is also the least dense and least compact; the reason of which is, that no vitreous matter can be smooth and denfe internally, unless it has been completely fufed. But if the denfity and fhining appearance of the internal furface of the Saxon porcelain were only the effects of the fusion of a vitreous matter, how could we conceive that veffels formed of that matter fhould have sustained the neceffary fufion for giving this denfity and fhining_appearance, without having entirely loft their fhape? The impoffibility of this is evident to any perfons who have been converfant in these matters and in the fufion of glafs. 24 Difference between oriental This quality of the Saxon porcelain must therefore Saxon and proceed from another caufe. It does indeed contain, as every porcelain does, particularly thofe of China and porcelain Japan, a fufible fubftance, which has been even completely fufed during the baking. Its denfity alfo, and its internal luftre, proceed chiefly from this fufed matter: but we are alfo certain, that it contains a large quantity of a fubftance abfolutely unfufible, from which it receives its admirable whiteness, its firmnefs and folidity, during the baking; in a word, which fupplies the place of the oriental kao-lin, and which has the property of contracting its dimenfions confiderably while it incorporates with the fusible substance. If it be fubjected to the most decifive trial, namely, the action of a violent fire, capable of melting every porcelain compoChem. Dia. fed of fufible matters alone, "I affirm (fays Mr Macquer), after many experiments, that it cannot be fufed, unlefs by a fire capable alfo of melting the beft Japanefe porcelain." The Saxon porcelain is therefore not to be confounded with those which are vitreous and fufible; but is in its kind as excellent as that of Japan, and perhaps fuperior, as we shall fee when we enume 4 POR rate the qualities which conftitute the excellence of por. Porcelain. celain. The subject of Mr Reaumur's fecond error, or at leaft that which he has not fufficiently explained, is is a fine talky powder, from the mixture of which with the kao-lin of China. According to him, this matter pe-tun-tfe the oriental porcelain is formed. Poffibly a very finely ground talky fubftance mixed with pe-tunperfons acquainted with the manufacture of any porcetfe might form a porcelain fimilar to the oriental; but lain muft perceive the impoffibility of forming vessels, unless the pafte of which they are made be fo ductile and tenacious that it may be worked upon a potter's lathe, or at leaft that it may be moulded. But talks, or any kinds of ftones, however finely ground, cannot acquire the requifite tenacity, which clays only, of all known earthy fubftances, poffefs. The Chinese porcelain veffels evidently appear to be turned fince they retain the marks of it: hence they must have been formed of a very tenacious paste, and confeupon the lathe, quently the kao-lin is not a purely talky matter, but is mixed with clay; or else the pe-tun-tfe and kao-lin are not, as Mr Reaumur fuppofes, the only ingredients of which Chinese porcelain is formed, but a fufficient quantity of fome binding matter, unknown to Father d'Entrecolles and Mr Reaumur, must be alfo added. 25 different Although, fince Mr Reaumur, no fcientific perfon Manufacte has written concerning porcelain, many have attempted ries of por most all the ftates of Europe. to make it. Manufactories have been established in al-celain in which has been long established, porcelain is also made Befides that of Saxony, countries. at Vienna, at Frankendal, and lately in the neighbourhood of Berlin. All these German porcelains are fimilar to the Saxon; and are made of materials of the fame kind, although they differ fomewhat from each other. England and Italy alfo have their porcelains, the chief of which are thofe of Chelsea and of Naples. M. de la Condamine, in his laft journey into Italy, vifited a manufacture of porcelain established at Florence by the marquis de la Ginori, then governor of Leghorn. M. de la Condamine obferved particularly the large fize of fome pieces of this porcelain. He fays he faw ftatues of the fineft antiques. The furnaces in which the porand groups half as large as nature, modelled from fome celain was baked were conftructed 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 quali ties of the best Chinese porcelain. A whiter glazing would be defirable, which they might probably attain, if the Marquis Ginori was not determined to use those materials only which were found in that country. made to difcover porcelain, or fo many manufactories But in no ftate of Europe have fuch attempts been of it been established, as in France. Before even Mr Reaumur had published on this fubject, porcelain was Paris, which was of the vitreous and fufible kind, but made at St Cloud, and in the suburb of St Antoine at/ confiderably beautiful. Since that time, confiderable manufactories of it have been established at Chantilly, at Villeroi, and at Orleans; the porcelains of which have a diftinguished merit. But the porcelain produced in the king's manufacture at Sevres holds at prefent the firft rank from its fhining white, its beautiful glazing, and coloured grounds, in which no porcelain has Porcelain. has ever equalled it. The magnificence of the gilding, the regularity and elegance of its forms, furpals every thing of the kind. 26 M. Guet coveries. Mr Guettard has published an account of his difco, tard's dif veries on this fubject, in the Memoirs of the Academy of Sciences for the year 1765. The kao-lin which he employed was a white argillaceous earth, filled with mi ca, which he found in the neighbourhood of Alençon; and his pe-tun-tfe is a hard, quartzofe, grit ftone, found abundantly in the fame country, with which the ftreets of Alençon are paved. We alfo know that Mr Guet tard had begun to make his experiments on porcelain with these materials in the year 1751, together with the then Duke of Orleans, to whom he was attached. The Count de Lauraguais, of the Academy of Sciences, engaged in the purfuit of porcelain for feveral years with uncommon ardour and constancy. He spared no trouble nor expence to attain his purpose, which was to make porcelain equal in all refpects to that of China and Japan. He showed fome pieces made by him in the year 1766 to the members of the Academy of ScienThe perfons appointed by them to examine it gave their opinion, "that of all the porcelains made in the country, that of the Count de Lauraguais molt refembles the porcelain of China and Japan in folidity, grain, and unfufibility." It were to be wished that it poffeffed equally the other qualities effential to the excellence of porcelain, namely, the whitenefs and luftre obfervable in the ancient Japanese porcelain. 27 In what the perfection of porcelain confilts. ces. We fhall now fhow what thofe qualities are which conftitute the perfection of porcelain. We must first forcelain carefully diftinguish the qualities which only contribute to the beauty and external appearance, from the intrinfic and effential properties in which the goodnefs and folidity of porcelain confift. All perfons who have made experiments in this way have foon difcovered the poffibility of making compounds very white, beautifully femi-transparent, and covered with a fhining glazing; but which cannot be worked for want of tenacity, are not fufficiently compact, are effentially fufible, are fubject to break by fudden application of heat and cold; and, laftly, the glazing of which cracks, becomes rough, and confequently lofes its luftre by ufe, because it is too foft. 28 Stone-ware On the other fide, we fhall alfo find it not difficult to compofe very tenacious pattes which fhall be capable of being eafily worked and well baked; which in the baking hall acquire the defirable hardness and denfity; which are unfufible, and capable of fuftaining very well the fudden 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 fhall foon fee that the materials fit for the compofition of fuch porcelains may be found abundantly in every country. The only difficulty, then, in this inquiry concerning porcelain, is to unite beauty and goodnefs in one Compofition; and indeed nature feems to be very fparing of materials fit for this purpose, and therefore perfect porcelain will always be a dear and valuable commodity. Thofe potteries which we call ftone-ware are not of a kind of modern invention, and have all the effential qualities of porcelain. the best Japanese. For if we except whitenefs, on which alone the femi-transparency depends, and compare all the properties of Japanese porcelain with thofe of our ftone-ware, no difference can be found betwixt them. Porcelain. The fame grain appears internally in both; the fame found is produced by ftriking them when properly fuf. pended; the fame denfity, the fame hardness by which they ftrike fire with teel, the fame faculty of fuftaining the heat of boiling liquors without breaking, and the fame unfufibility in fire, are obfervable. Laitly, if the earths of which ftone-ware is made were free from heterogeneous colouring matters, which prevent their white. nefs and femi-transparency; if veffels were carefully formed; if all the proper attentions were given; and if thefe veffels were covered over with a fine glazing-they would be as perfect porcelain as that of Japan. The most perfect porcelain, therefore, is nothing else than a fine white ftone-ware. Earths of this kind are probably more rare in Europe than in Japan and China. And probably also the want of thefe earths was the caufe that the firit makers of porcelain in this country confined themselves to an external imitation, by employing nothing but vitrifiable matters with fufible falts and a small quantity of white earth, from which fufible and vitreous porcelains were compofed, which might be called falfe porcelains. But Genuine things are much changed fince thefe first attempts. Be-porcelain fides the difcoveries of the Count de Lauraguais and of made in Mr Guettard, genuine white porcelains have been made to a long time ago in Germany, efpecially in Saxony and Europe. at Frankendal. Thefe porcelains are not inferior in any refpect to the oriental; they are even much fuperior in beauty. and whitenefs to the modern oriental porcelain, which has much degenerated in thefe refpects; they feem even to excel the oriental in the most valuable quality of porcelain, namely, the property of fuftaining the fudden change of heat and cold. We cannot judge of the quality of porcelain by a flight trial: for fo many circumftances concur to make a piece of porcelain capable or incapable of fuftaining the fudden application of heat and of cold, that if at the fame time boiling water be poured into two veffels, one of which is good porcelain and the other bad, the former may poffibly break and the latter remain entire. The only true method of dif covering good porcelain in this refpect is, to examine feveral pieces of it which are daily used; for instance, a fet of coffee-cups. But it has been observed, that in many fuch 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. 29 fome coun 35 Every one talks of porcelain, and yet few are con. Excellency noiffeurs of it. None can be confidered as fuch but thofe of the anwho have long made it an object of their inquiries, nefe porce cient JapaThat the ancient Japanese porcelain is the moft perfect lain. is a a general opinion. This porcelain is indeed very beautiful, and we muft alfo 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 perfons believe never can be equalled. Some perfons even decry the Saxon porcelain for a quality which really gives it a fuperiority to the Japanese, namely, the greater smoothness, luftre, and lefs granulous appearance of its internal furface than the oriental. The refem blance of this furface to that of glass has evidently fuggefted this notion; and it would be well founded if the denfity more and more till the porcelain is baked, that is, till Porcelain. it has acquired its proper hardnefs and tranfparency; which is known by taking out of the furnace from time to time, and examining, fmall pieces of porcelain, placed for that purpofe in cafes which have lateral openings. When thefe pieces thow that the porcelain is fufficiently baked, the firft is no longer to be fupplied with fuel, the furnace is to be cooled, and the porcelain taken out, which in this ftate refembles white marble not having a fhining furface, which is afterwards to be given by covering them with a vitreous compofition called the glazing. Porcelain, denfity and luftre of this porcelain proceeded only from a fufible and vitreous quality; but as they do not, and as this porcelain is as fixed and as unfufible as the Japanese, its density, fo far from being a fault, is a valuable quality: for we muft allow, that of porcelains equal in other refpects, thofe are beft which are moft firm and compact. Hence the interior fubftance of the Japanese porcelain is esteemed for its greater denfity, compactnefs, and luftre, than our vitreous fand or fritt porcelains; becaufe thefe qualities indicate greater cohefion, and more intimate incorporation of its parts. For the fame reafon alfo the fuperior denfity of the Saxon porcelain ought to give it the preference to the Japanese. Befides, nothing would be eafier than to give the Saxon porcelain the granulous texture of the Japanefe, by mixing with the paste a certain quantity of fand. But the perfons who perfected that manufacture were certainly fenfible that fuch a conformity to the Japanese porcelain would leffen 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 fand, flints, or other matters of that kind. 31 vitreous What we have faid concerning porcelain in general, and the principal kinds of it, feems fufficient to give just notions of it, if not to perfons who without confidering the fubject are determined to prefer the most ancient, to thofe, at least, who have made experiments on this fubject, or who, having a fufficient knowledge ef chemistry, are capable of ftudying and examining it thoroughly. We fhall finish this article by giving a fhort defeription of the method of manufacturing porcelain as practifed in Europe. Of making The bafis of the porcelains which we have called fufatible or fible, vitreous, or falfe porcelains, is called by artifts a fritt; which is nothing else than a mixture of fand or Porcelains. of powdered flints, with falts capable of difpofing them to fufion, and of giving them a great whiteness by means of a fufficient heat. This fritt is to be then mixed with as much, and no more, of a white tenacious earth of an argillaceous or marly nature, than is fufficient 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 pafte, which is to be formed, either upon the wheel or in moulds, into pieces of fuch forms as are required. Each of thefe pieces, when dry, is to be put into a cafe made of earthen ware (A); which cafes 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 fizes; and are fo disposed, that their fire-place is placed on the outfide oppofite to one or more openings, which communicate within the furnace. The flame of the fuel is drawn within the furnace, the air of which rarefying, 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 32 The porcelain when baked and not glazed is called Porcelain bifcuit, which is more or lefs beautiful according to the fculptures. nature of the porcelain. The manufacture of Sévres excels all others in this refpect, and it is therefore the only one which can produce very fine pieces of fculpture; that is, in which all the fineness of the workmanship is preferved, and which are preferable in smoothness and whiteness to the finest marble of Italy. As no piece of fculpture of this kind can preferve all the delicacy of its workmanship when covered with a glazing, and as fculptors avoid polifhing their marble figures, because the luftre of the polish is difadvantageous; therefore, in the manufactures of Sévres, all figures or little ftatues, and even fome ornamental vafes, are left in the ftate of bifcuit. The other pieces of porcelain are to be glazed in the following manner. 33 A glafs is firft to be compofed fuited to the nature Method of of the porcelain to which it is to be applied; for every glazing of glafs is not fit for this purpofe. We frequently find porcelain that a glafs which makes a fine glazing for one porcelain fhall make a very bad glazing for another porcelain; fhall crack in many places, fhall have no luitre, or fhall contain bubbles. The glazing, then, muft be appropriated to each porcelain, that is, to the hardness and denfity of the ware, and to the ingredients of its compofition, &c. Thefe glazings are prepared by previously fusing together all the fubftances of which they confift, fo as to form vitreous maffes. Thefe maffes are to be ground very finely in a mill. This vitreous powder is to be mixed with a fufficient quantity of water, or other proper liquor, fo that the mixture fhall have the consistence of cream of milk. The pieces of porcelain are to be covered with a thin ftratum of this matter; and when very dry, they are to be again put into the furnace in the fame manner as before for the forming of the biscuit, and to be continued there till the glazing be well fufed. The neceffary degree of fire for fufing the glazing is much less than that for baking the patte. The pieces of porcelain which are intended to remain white are now finished; but those which are to be painted and gilded muft undergo further operations. The colours to be applied are the fame as thofe used for enamel painting. They all confift of metallic calces bruifed and incorporated with a very fufible glass. Cro cus (A) The cafes are called by English potters feggars. They are generally formed of coarfer clays, but which muit be alfo capable of fuftaining the heat required without fufion. By means of these cafes the contained porcelain is preferved from the fmoke of the burning fuel. The whiteness of the porcelain depends much on their compactness of texture, by which the fmoke is excluded, and on the purity of the clay of which they are made. 3 ᄂ 227. in front, it was called a tetraflyle; when fix, hexaftyle; Porch when eight, odoflyle, &c. PORCH, in Greek loa, a public portico in Athens Porella. adorned with the pictures of Polygnotus and other eminent painters. It was in this portico that Zeno the philofopher taught; and hence his followers were called Stoics. See STOICS and ZENO. Porcelain, eus of iron furnishes a red colour; gold * precipitated Porch. by tin makes the purple and violet; copper calcined by *See Che acids and precipitated by an alkali gives a fine green; mifry, zaffre makes the blue; earths flightly ferruginous produce a yellow; and, laftly, brown and black colours are produced by calcined iron, together with a deep blue of zaffre. Thefe colours being ground with gum-water, or with oil of fpike, are to be employed for the painting of the porcelain with defigns of flowers and other figures. For gilding, a powder or calx of gold is to be applied in the fame manner as the coloured enamels. The painted and gilded porcelains are to be then expofed to a fire capable of fufing the glafs, with which the metallic colours are mixed. Thus the colours are made to adhere, and at the fame time acquire a glofs equal to that of the glazing. The gold alone has not then a fhining appearance, which muft be afterwards given to it by burnishing with a blood-ftone. 34 Prepara tion of unfufible porcelain. The operations for the unfufible porcelains, and alfo for fuch as are of the nature of ftone-ware, are fomewhat more fimple. The fands and ftones 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 fufficient heat to give them fuch a folidity 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 difpofition aflifts 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 fuch a quantity of water, that the liquor fhall have the confiftence of milk. The pieces of porcelain are haftily dipt in this liquor, the water of which they imbibe, and thus on their furface is left an uniform covering of the glazing materials. This covering, which ought to be very thin, will foon become fo 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 raifed to fuch a height, that all within the furnace fhall be white, and the cafes fhall be undiftinguishable from the flame. When, by taking out small pieces, the porcelain is known to be fufficiently baked, the fire is difcontinued, and the furnace cooled. If the baking has been well performed, the pieces of porcelain will be found by this fingle operation to be rendered compact, fonorous, clofe-grained, moderately gloffy, and covered externally with a fine glazing. The painting and gilding of this porcelain are to be executed in a manner fimilar to that already defcribed. PORCEL IN-Shell, a fpecies of CYPREA. PORCH, in architecture, a kind of veftibule fupported by columns; much ufed at the entrance of the ancient temples, halls, churches, &c. A porch, in the ancient architecture, was a veftibule, or a difpofition of infulated columns ufually crowned with a pediment, forming a covert place before the principal door of a temple or court of juftice. Such is that before the door of St Paul's, Covent Garden, the work of Inigo Jones. When a porch had four columns VOL. XV. Part I. PORCUPINE, in zoology. See HYSTRIX. PORCUPINE-Man, the name by which one Edward Lambert, who had a distempered fkin, went in London. We have the following account of him in the Philofophical Tranfactions for 1755, by Mr Henry Baker, F. R. S. " is now (fays he) 40 years of age, and it is 24 years fince he was firft fhown to the fociety. The fkin of this man, except on his head and face, the palms of his hands, and the foles of his feet, is covered with excrefcences that refemble an innumerable company of warts, of a brown colour and cylindrical figure; all rifing to an equal height, which is about an inch, and growing as clofe as poffible to each other at their bafis; but fo ftiff and elaftic as to make a rustling noife when the hand is drawn over them. These excrefcences are annually shed, and renewed in fome of the autumn or winter months. The new ones, which are of a paler colour, gradually rise up from beneath as the old ones fall off; and at this time it has been found neceffary for him to lofe a little blood, to prevent a flight fickness which he had been used to fuffer before this precaution was taken. He has had the fmallpox, and he has been twice falivated, in hopes to get rid of this difagreeable covering; but though juft when the puftules of the fmallpox had fcaled off, and immediately after his falivations, his fkin appeared white and fmooth, yet the excrefcences foon returned by a gradual increase, and his skin became as it was before. His health, during his whole life, has been remarkably good but there is one particular of this cafe more extraordinary than all the reft; this man has had fix children, and all of them had the fame rugged covering as himself, which cane on like his own about nine weeks after the birth. Of thefe children only one is now living, a pretty boy, who was shown with his father. It appears, therefore, as Mr Baker remarks, that a race of people might be propagated by this man, as different from other men as an African is from an Englishman; and that if this fhould have happened in any former age, and the acci. dental original have been forgotten, there would be the fame objections against their being derived from the fame common ftock with others: it must therefore be admitted poffible, that the differences now fubfifting between one part of mankind and another may have been produced by fome fuch accidental caufe, long af ter the earth has been peopled by one common progenitor." PORE, in anatomy, a little interftice or space between the parts of the skin, ferving for perfpiration. PORELLA, in botany; a genus of the natural order of mufci, belonging to the cryptogamia clafs of plants. The anthere are multilocular, full of natural pores, with an operculum; there is no calyptra, nor pedicle; the capfules contain a powder like thofe of the other moffes; and their manner of shedding this powder is not by separating into two parts, like those of the selago and lycopodium, but by opening into feveral holes on all fides. 3 D POREN |