656 NEW YOKK STATE MUSEUM 



pan. According to tlie type of machine used, it is possible tO' disin- 

 tegrate a clay in its dry, plastic, or even very wet condition. There 

 are many devices for this kind of work, bnt only a few need be men- 

 tioned. 



Dry methods of preparation 



Crushers. The Blake type of crusher, which is frequently used 

 for breaking up hard shales or old brick, consists of two jaws, the 

 one fixed, the other fastened at its lower end, while the upper end 

 moves back and forth at a rapid rate. Such crushers are strong 

 and effective, but have a rather limited use at clay-working estab- 

 lishments. 1 



Pan crushers. Of these there are two classes, dry pan crushers 

 and wet pan crushers. The former pulverizes the material as it 

 conies from the bank, the latter tempers it with water. In either 

 case the crushers consist of a circular pan in which two iron wheels 

 revolve on a horizontal axis. They are made to revolve by friction 

 against the pan, which is rotated by steam power. In a dry pan 

 the bottom is perforated; the wheels weigh 2000 to 5000 pounds 

 each. The wet pan has a solid bottom, in which there is a door 

 through which the material can escape when sufficiently tempered. 



A good dry pan will grind 100 tons in lOi hours through one 

 eighth inch screens.-^ 



Two scrapers are placed in front of the rollers to throw the ma- 

 terial in their path. 



Disintegrators. These, of which the Stedman disintegrator is a 

 good type, consist of several series of concentric drums which re- 

 volve in different directions. The material to be pulverized is fed 

 into the disintegrator by means of a hopper, and as soon as it enters 

 is caught between the staves of the first drum, and thrown by this 

 against the next inner one, which revolves in the opposite direc- 

 tion, and from this one against a third inside of the second, revolv- 

 ing in the same direction as the first. The clay particles by being 

 violently thrown against the staves and against each other are 



1 Ohio geol. sur. 1893 p. 142. E. Orton jr. Clays and clay-working in- 

 dustries of Ohio. 



