PORCELAIN. 255 PORCH. Johann Friedrich BiJttger. In 1756 the S6vres factory was established bj' royal decree as a con- timiation and development of the earlier factory at Viucennes, and in 1768, the actual porcelain clay having been discovered a few years earlier, the hard porcelain was manufactured at S6vres. The establishment has maintained its graceful ork without intermission, even during the Revo- lution, and the style of decoration has changed as the difl'erent directors have sought for new systems of design. The productions of the manu- factories can always be purchased, except when made especially for national gifts to friendly powers or puljlie benefactors, but the prices are high and no promise can 1)6 made as to the time of delivery. At present, since 1898, the old .sys- tems of design have been largely abandoned and a very elaborate development of independent thought in the decoration is in progress. Among the most remarkable of its movements are the unglazed pieces kno^-n commonly as biscuit figures, which are found modeled by the first sculptors of France. These are sometimes six- teen or twenty inches high, and groups or series of them are prepared for the adornment of the table at a stately banquet or for similar uses. There are two different hard porcelains made: one which approaches very nearly in quality and color, and in the degree of heat needed to fire it, to Chinese porcelain; the other a still harder ware fired at a very high temperature and of course limited in its coloration, as few pig- ments are available. In England, in the eigh- teenth century, the true porcelain was made in at least two towns, Plymouth and Bristol, and many other manufactories were started in the first half of the nineteenth century. It is since 1850, however, that English porcelain has be- come an important industrial product. There is no national establishment, and therefore the wares made are all for the market and artistic advance is not steady. Proces.se.s of Manufacture. Porcelain is made by firing together two natural materials which are knoHTi by Chinese names, kaolin and petuntze, al- though the deposits found in Europe are not com- monly of exactly the same chemical nature as the Chine-se. The latest careful writer on the subject, William Burton, says expressly that the kaolin has been produced by the gradual decomposition of the petuntze: and it is admitted that the two natural substances, the harder and more rock-like petuntze and the clay-like kaolin, are of the same general composition. The body is generally made of the kaolin just as any piece of pottery is modeled in common clay, and the fusible petuntze forms the glaze, but with this peculiarity in the process, that body and glaze are fired together. This is exceptional in the ceramic art, because in most varieties of pottery the glaze is applied separately and fired separatel.y and at a much lower temperature. The temperature needed for the firing of true porcelain is about 1400° Centi- grade, or more than 3000° Fahrenheit. The few pigments that will bear this great heat are ap- plied on the body and under the glaze. Paintings in vivid colors are nearly always of the nature of enamel applied upon the glaze and showing plainly as in slight relief, or else as having a surface altogether difl'erent from that of the glaze, and usually much less brilliant. BiBLiOGBAPHT. Treatises on porcelain are usually to be found in the books devoted to ceramic ware in general. ( See the bibliography of Pottery.) A few have been devoted to this spe- cial ware, and the most celebrated of these is the work of Jacquemart and Le Blant, Ilistoire arlis- tique, industrielle et commerciale de la porce- laiiie (Paris, 1862). This work has been in part superseded by more recent treatises, but is famed for the admirable illustrations from etched plates by Jules Jacquemart. Chinese porcelain has beea treated in two French books. La ceramique chi- noise, by Grandidier (Paris, 1894), and La porce- laine de Chine, by O. Du Sartel (ib., 1881) ; these works are large quartos with many plates. The work devoted to the Walther collection in Baltimore, whose chief author is Doctor Steven W. Bushell, contains a more profound study of the subject than any other work, and its illustrations are admirable chromolithogi-aphs. The same distinguished expert has aided in the publication of A. History and Description of Chinese Porcelain, by Cosmo ilonkhouse (New York, n.d., about 1901). The publications con- nected with the S6vres manufactory are impor- tant, especially La manufacture natioiuile de Sevres, exposition universeUe de 1900, having a carefully prepared text, and a number of excel- lent plates illustrating the most recent produc- tions. A History and Description of English Porcelain, by William Burton (New York, n.d., preface dated 1902), is a really critical treatise, as is also the popular treatise by Lelmert, Das Porzeltan (Bielefeld, 1902). PORCELAIN TOWER. An octagonal struc- ture iu Nanking, China, erected in the early part of the fifteenth century. It had nine stories, faced with variegated porcelain, from which bells and lamps were hung. The tower was de- stroyed by the Taipings in 1853. !Many minia- ture reproductions are in existence, among them those in the Green Vault in Dresden. PORCELANITE, or Porcelain-Jasper. A metamorphic rock of the granite group which is formed by the baking of argillaceous beds. It has the fracture of flint, and is gray to I'ed in color, somewhat resembling jasper, from which it differs, however, in being more fusible. PORCH (OF., Fr. porche, from Lat. porticus, porch, gallery, from porta, gate) . An open lobby, vestibule, or room, affording entrance to a build- ing, and usually built as an accessory to the main mass and projecting from it. The porch of a church may be a gabled building, small and low in comparison with the church proper, with a single door of entrance and a single passage-like interior with peraianent seats along the sides; or it may be a mere roof, vaulted or of wooden frame-work, resting upon a pair of columns, as often in the churches of Lombardy: or it may be as long as the whole church is wide, as in the narthex of Eastern churches, or the great vesti- bule of Saint Peter's at Rome. Such great porches as these will naturally be more or less closely united to the main structure, as they are high and as it is common to build a series of rooms or a gallery above them : they are, there- fore, more properly vestibules than porches, though the latter term is more generally applied to them. The projecting porches of Gothic churches add much to their variety of outline and often receive
