Electrical products Carborundum. 217 



and afterward carried into kilns and burned 

 the same as ordinary pottery or porcelain. 

 These wheels vary in size from one to sixteen 

 inches. The substances used as a bond in 

 manufacturing wheels are kaolin, a kind of 

 day, and feldspar. 



While carborundum has already a large 

 place as a commercial product, there is no 

 doubt but that the uses to which it will be 

 put will vastly increase as time goes on. This 

 product may be called an artificial one, and 

 m-ver would have been known had it not been 

 for the intense heating effects that are ob- 

 tained from the use of electricity. It certainly 

 never could have been brought into play as 

 one of the useful agencies in manufacturing 

 and the arts. It is not known to exist as a 

 natural product, which at first thought would 

 seem a little strange in view of the evidences 

 of intense heat that at one time existed in the 

 earth. Its absence in nature is explained by 

 Mr. l-'it/jrerald by the fact that " the tempera- 

 tures of formation and of decomposition lie 

 very close together," 



