CERAMICS. 467 



The glaze, Jap. Kusuri, is prepared from the argillaceous flux 

 (felspar, pegmatite, porcelain stone) used in the factory, by careful 

 sorting and working into a fine paste together wood ashes cleared 

 from their lye. For porcelain, common Isu-bai, the ashes from 

 the bark oi Distyliiim racemosiun, S. and Z. (see page 251) is used, 

 following the example of Arita ; for stone-ware, usually Nara-no- 

 hai, oak-wood ashes from QiierciLs glandiilifera, Bl., or Kuri-no-hai, 

 from the wood of Castanca vulgaris, Lamk. (see page 244). Dr. 

 Sarnow, to whom I gave a sample of Isu-bai which I had brought 

 with me for analysis, found in it the following proportions : 38-27 

 parts lim.e, 3-90 magnesia, 0'66 manganous carbonate, 0*24 iron 

 oxide, ^•2'^ potash, 10*65 silicic acid, 3'6i phosphoric acid, 1*27 

 sulphuric acid, 0*45 chlorine, 26'85 carbonic acid, 3*59 parts sand 

 and 2*6 1 water. As the ashes of oak and chestnut woods are also 

 rich in lime, it follows that the glazes used in Japan for porcelain 

 and stone-ware form a transparent glass, rich in lime, whose com- 

 position varies, but is closely related to that of the material to be 

 glazed, with which it must unite perfectly. 



The porcelain furnaces used for the chief or second firing consist 

 of a row of vaults of no regular number or size, but governed by 

 requirements. There are usually, however, five to ten of them, 

 placed behind and somewhat above each other on an inclined plane, 

 so that the sill of each lies about 80 or 90 centimeters higher than 

 the one before it. In large establishments, each vault is 2 Ken (3"64 

 meters) long, 3 Ken (5-46 meters) broad, and 8 Shaku (2-43 meters) 

 high. The fire boxes are narrow passages, as in the biscuit kiln, 

 near the boundary between the two arches, each of which has a 

 special draft hole in the upper part of the arch, and on the same 

 side with the opening where the fire is fed. The floor of the porce- 

 lain chamber is covered with sand, and in the final firing of the 

 wares, part of them are placed in fire-proof cases, and part without, 

 the article being placed only on a fire tile. When all is ready for 

 the burning, the principal fire is lighted in the lowest arch and 

 kept up from 6 to 1*2 hours. The other fires are now lighted 

 gradually at intervals of one or two hours, so that really the firing 

 lasts fully 24 hours, and then follows cooling, for which from 3 to 6 

 days must be allowed. The flames of the lowest fire circulate 

 as in the biscuit furnace, the hot gases pass through the draft 

 holes 80 to 90 centimeters high up on the wall, into the second 

 arch at its floor, conformably to its higher position, and so on 

 through the series of arches. When the fire in one arch goes out, 

 the outward openings are all closed up. The necessary degree of 

 heat for burning the wares is learned by practice ; it must be so 

 great in the upper arches, that a billet of wood held in one of the 

 testing places is at once kindled. 



A large well-constructed furnace of fire clay can be built for from 

 about £\^ \.o ;^20, and lasts twelve or fifteen years. It is covered 

 with a light roof for protection from rain and violent winds. In 



