English porcelain or china

—Most of this belongs to the cla called tender or soft porcelain by the French and German manufacturers. It is not, therefore, composed simply of kaolin and petuntse . The English china is generally baked at a much lower heat than that of Sèvres, Dresden, and Berlin; and it is covered with a mere gla . Being manufactured upon a prodigious scale, with great economy and certainty, and little expenditure of fuel, it is sold at a very moderate price compared with the foreign porcelain, and in external appearance is now not much inferior. Some of the English porcelain has been called ironstone china. This is composed usually of 60 parts of Cornish stone, 40 of china clay, and 2 of flint gla ; or of 42 of the felspar, the same quantity of clay, 10 parts of flints ground, and 8 of flint gla . The glaze for the first composition is made with 20 parts of felspar, 15 of flints, 6 of red lead, and 5 of soda, which are fritted together; with 44 parts of the frit, 22 parts of flint gla , and 15 parts of white lead, are ground. The glaze for the second composition is formed of 8 parts of flint gla , 36 of felspar, 40 of white lead, and 20 of silex (ground flints). The English manufacturers employ three sorts of compositions for the porcelain biscuit; namely, two compositions not fritted; one of them for the ordinary table service; another for the de ert service and tea dishes; the third, which is fritted, corresponds to the paste used in France for sculpture; and with it all delicate kinds of ornaments are made. | First composition. | Second composition. | Third composition. | | Ground flints | 75 | | 66 | Lynn sand | 150 | | Calcined bones | 180 | | 100 | | 300 | | China clay | 40 | | 96 | | 100 | | Clay | 70 | Granite | 80 | Potash | 10 | The glaze for the first two of the preceding compositions consists of, felspar 45, flints 9, borax 21, flint gla 20, nickel 4. After fritting that mixture, add 12 parts of red lead. For the third composition, which is the most fusible, the glaze must receive 12 parts of ground flints, instead of 9; and there should be only 15 parts of borax, instead of 21. PLAN OF AN ENGLISH POTTERY. A stoneware manufactory should be placed by the side of a canal or navigable river, because the articles manufactured do not well bear land carriage. A Staff ords hire pottery is usually built as a quadrangle, each side being about 100 feet long, the walls 10 feet high, and the ridge of the roof 5 feet more. The base of the edifice consists of a bed of bricks, 18 inches high, and 16 inches thick; upon which a mud wall in a wooden frame, called pisé , is raised. Cellars are formed in front of the buildings, as depôts for the pastes prepared in the establishment. The wall of the yard or court is 9 feet high, and 18 inches thick. IMG:4147767755307473660_illo1021.png:Plan of pottery Fig. 899. A , is the entrance door; B , the porter’s lodge; C , a particular warehouse; D , workshop of the plaster-moulder; E , the clay depôt; F , F , large gates, 6 feet 8 inches high; G , the winter evaporation stove; H , the shop for sifting the paste liquors; I , sheds for the paste liquor tubs; J , paste liquor pits; K , workshop for the moulder of hollow ware; L , ditto of the dish or plate moulder; M , the plate drying-stove; N , workshop of the biscuit-printers; O , ditto of the biscuit, with o′ , a long window; P , pa age leading to the paste liquor pits; Q , biscuit warehouse; R , place where the biscuit is cleaned as it comes out of the biscuit kilns, S S ; T , T , enamel or glaze kilns; U , long pa age; V , space left for supplementary workshops; X , space appointed as a depôt for the sagger fire-clay, as also for making the saggers; Z , the workshop for applying the glaze liquor to the biscuits; a , apartment for cleaning the glazed ware; b , b , pumps; c , basin; d , muffles; e , warehouse for the finished stoneware; f , that of the glazed goods; g , g , another warehouse; h , a large space for the smith’s forge, carpenter’s shop, packing room, depôt of clays, saggers, . The packing and loading of the goods are performed in front of the warehouse, which has two outlets, in order to facilitate the work; i , a pa age to the court or yard; l , a space for the wooden sheds for keeping hay, clay, and other miscellaneous articles, m , room for putting the biscuit into the saggers; m′ , a long window; n , workshop with lathes and fly-wheels; o , drying-room; p , room for mounting or furnishing the pieces; q , repairing room; r , drying room of the goods roughly turned; s , rough turning or blocking-out room; t , room for beating the paste or dough; u , counting-house. The declared value of the earthenware exported in 1836, was 837,774 l. ; in 1837, 558,682 l. There are from 33,000 to 35,000 tons of clay exported annually from Poole, in Dor sets hire, to the English and Scotch potteries. A good deal of clay is also sent from Devons hire and Cornwall. The Spanish alcarazzas , or cooling ve els, are made porous, to favour the exudation of water through them, and maintain a constantly moist evaporating surface. Last eyrie says, that granular sea salt is an ingredient of the paste of the Spanish alcarazzas; which being expelled partly by the heat of the baking, and partly by the subsequent watery percolation, leaves the body very open. The biscuit should be charged with a considerable proportion of sand, and very moderately fired.