DESCRIPTION OF THE PORCELAIN MILL

IMG:4147767755307473660_illo1025.png:Porcelain mill Fig. 900 enlarged (192 kB) 1. The following figures of a felspar and flint mill are taken from plans of apparatus lately constructed by Mr. Hall of Dartford, and erected by him in the royal manufactory of Sèvres. There are two similar sets of apparatus, fig. 900. , which may be employed together or in succe ion; composed each of an elevated tub A , and of three succe ive vats of reception A ′, and two behind it, whose top edges are upon a lower level than the bottom of the casks A , A , to allow of the liquid running out of them with a sufficient slope. A proper charge of kaolin is first put into the cask A , then water is gradually run into it by the gutter adapted to the stopcock a , after which the mixture is agitated powerfully in every direction by hand with the stirring-bar, which is hung within a hole in the ceiling, and has at its upper end a small tin-plate funnel to prevent dirt or rust from dropping down into the clay. The stirrer may be raised or lowered so as to touch any part of the cask. The semi-fluid ma is left to settle for a few minutes, and then the finer argillaceous pap is run off by the stopcock a′ , placed a little above the gritty deposit, into the zinc pipe which conveys it into one of the tubs A ′; but as this semi-liquid matter may still contain some granular substances, it must be pa ed through a sieve before it is admitted into the tub. There is, therefore, at the spot upon the tub where the zinc pipe terminates, a wire-cloth sieve, of an extremely close texture, to receive the liquid paste. This sieve is shaken upon its support, in order to make it discharge the washed argillaceous kaolin. After the clay has subsided, the water is drawn off from its surface by a zinc syphon. The vats A ′ have covers, to protect their contents instead of the hand. A vertical shaft, with horizontal or oblique paddles, is made to revolve in the vats for this purpose. IMG:4147767755307473660_illo1026a.png:Small triturating wheel