168 " NEW YORK STATE MUSEUM 



crusjier which reduces them to smaller pieces, they then pass 

 through a smaller crusher; and from there they pass succes- 

 sively oyer six sets of rolls. The idea is to crush as little as 

 possible each time, so that the minimum quantity of fine powders 

 is obtained, as the manufacture of wheels demands a large pro- 

 portion of the coarser grains. From the rolls the material is 

 passed through washers, then driers, and from the driers it goes 

 to the graders. Here it is screened, the various powders result- 

 ing from the screening being known by the number of meshes to 

 the square inch in the sieve through which they have passed. 

 The coarsest used is 14 and the finest 180. Between these two 

 limits the grades run 16, 20, 24, 30, 36, 46, 60, and then by tens 

 up to 180. 



In the Sapphire mills of the Hampden Emery Co. of Georgia 

 and North Carolina, where the material handled is embedded in 

 a soft chloritic matrix, the material on coming from the mine is 

 hoed with wooden hoes in inclined troughs filled with running 

 water. It is then crushed and passed over a 14 mesh sieve. 

 The portion which passes through the sieve is then treated by 

 what is known as the muller process. The crushed and 

 screened material is placed in a circular trough and is there 

 agitated by two heavy wooden rollers each 5 feet high. These 

 rollers are attached to a revolving shaft which rises through a 

 platform in the center of the trough. This trough is kept full 

 of water. The cleansing of the material is effected by the rub- 

 bing of the hard grains of emery one against the other, thus 

 wearing off the softer matrix, which, being light, is carried out 

 by the water flowing over the central platform, the heavy 

 emery remaining in the bottom of the trough. After being sub- 

 jected to this muller process for from three to five hours, the 

 material left in the bottom of the trough is removed and dried 

 by one of many hot air processes. In the Sapphire mills it is 

 dropped down a chimney on a soapstone slide a distance of about 

 20 feet. It is then crushed in rolls and sorted into various 

 grades by screening. 



