CLAY MANUFACTURES. 671 
made in a trial of skill on the part of the turner. As fast as the ware is 
made it is dried. In the country, this is done by setting a flat board 
covered with ware inthe sun. In the smaller potteries of Akron and 
elsewhere, various devices are adopted. The ware is piled into a net- 
work of shelves under which pass steam-pipes. The largest and best 
stone-ware works dry it in closets, exactly like those used in the white- 
ware or china works, which will be noticed later. 
The dry-ware is next “slipped”. This technical expression of the 
potter designates the covering of the ware with any wash or solution. 
Applied to stone-ware, it means the washing of the ware in water con- 
taining a very fine-grained clay in suspension, so that its surface is 
covered by a film of clay. These slip clays on heating vitrify readily 
to a black glass, and run freely on the ware, making a very handsome 
glaze. The chemistry of the process is obvious. A partial analysis of 
theAlbany, N. Y., “slip,” that is most largely used in the State, shows 
the following composition : 
Segquioxidevot arom™ (Hey) O))isccnc-eececcireseseesse) eects Nesseceaceenese) eencs 1.48 
TERA, Cg, ©))o00000900000600000090060000 000000000 +90006100000000.009000000000000000000% 3.17 
Stade, (Nl_ OD) -ce000000000000000006000800000:.0800090000080 desccctensesec tect ecneeseees 74 
5,34 
There is present besides a large amount of carbonates of lime and 
magnesia, which are undetermined. A clay full of the very finest silica 
and these impurities would, of course, fuse so readily that it would flow 
like a glaze at the vitrifying heat of stone-ware. Slip clay is found in 
various places in Ohio, but a great deal comes from outside points. Some 
of these clays fuse to a clear or nearly clear glass, in which case their 
fusibility is due to alkalies and earths alone. Some slips melt much 
easier than others, and potters have complained that their slip runs 
freely only at temperatures so high that the ware begins to lose shape. 
The judicious use of powdered feldspar, salt-water, or carbonates of 
soda or potash could easily correct this infusibility. The clear slips are 
best mixed with clays not readily fusible, but which are black in burn- 
ing. The product has both color and fusibility. The composition of 
these clays may be farther illustrated by the following analysis ofa 
“‘ Kaolite” slip-clay, for which thanks are due to Messrs. Whitmore, — 
Robinson & Co., of Akron, who use it in their works: 
