676 GEOLOGY OF OHIO. 
not of great importance in the State. The clays used are quite similar 
to the stone-ware clays, but are less liable to semivitrification and 
fretting, and hold their iron in combination in that peculiar state which 
gives the brick-red color to a clay instead of the distribution of a small 
part, and the occurrence of the rest in small grains as seen in stone- 
ware clay. There are also some drift clays used for this work. The | 
processes by which earthen-wares of this class are made are very 
simple. Materials like stone-ware, in shape and use, are fashioned 
mainly on a potter’s wheel ; flower-pots, etc., are made by similar means. 
The making of door-knobs forms an interesting phase of earthen-ware 
manufacture. The only two works in Ohio are in East Liverpool. The 
clays used are the native clays of that county, mainly from the Lower 
Kittanning horizon. There are two kinds used—a light clay, the same 
as the yellow-ware clay of this district, several grades of which are 
mixed to get a good body, and a clay obtained to the south-east of | 
Liverpool, in the Barren Measures, probably, which is naturally red, and 
which burns to a cherry-red color. These clays, to be properly pre- 
_ pared, are put through a process called boiling. The clays are put into 
a vertical cylinder, about 6 feet in diameter, in the center of which re- 
volves a rod carrying stirring and cutting arms, arranged spirally. 
This machine, filled with the requisite amounts of water and clay, is set 
in motion by horse-power ; the clay is beaten to a thin mud or “slip”. 
This is then run out in a fine stream, into a slightly inclined, oblong box, 
the bottom of which is covered by a fine bolting cloth. The sand, 
coarse grit, etc., is passed over the cloth and out at the end to a re- 
ceptacle provided ; the slip passes through into a large tank ; from here 
it is dipped, as fast as needed, into a large iron-lined pan twenty feet 
long by five feet wide, and one foot deep. A fireplace and flues circulate 
underneath the pan, and evaporate the water from the slip. One panful a 
day (about 5 tons) is concentrated. When removed from the pan the 
clay is as soft and plastic as itis possible to be; it is piled up and covered 
with wet blankets to keep it tempered. Lach color of clay is of course 
made separately. The clay, when ready to use, is next wedged. A 
block of both colors about 12/x12’’x6” is cut and sliced up by a wire 
into six or eight layers each; these are piled alternately into a new 
block one foot cube. This is lifted and thrown down with violence to 
consolidate the layers; it is then cut and welded again by a blow, and 
so on until the colors are marbled in fine alternating streaks. ‘This clay 
is then molded into the requisite shapes, by first wadding with the hands 
