CARBON AND SILICON. 



BY JAMES G. VAIL. 



Widely diflferent as are our physical relations to carbon and 

 silicon, the tendency is to forget the close relationship that 

 exists between them. Certain it is that both are vital factors 

 in the great economy of which we are a part, and a brief 

 review of some points of comparison may be not unprofitable. 



Carbon is the one element that occurs throughout the 

 animal and vegetable kingdoms; and, in comparison, it is 

 interesting to note that silicon occurs in nearly all geologic 

 formations. Following the suggestion that silicon is to the 

 inanimate world what carbon is to the animate, we should 

 remember that in the periodic system, by which the elements 

 are grouped into families by arranging them in the order of 

 their atomic weights, carbon stands next to silicon in the 

 family of elements which combine with two atoms of oxygen. 

 The oxides, in each case the most familiar occurrence of the 

 element, are exceedingly unlike physically — carbonic acid 

 gas, on the one hand, and quartz or sand on the other. This 

 probably accounts for our small tendenc}- to consider how 

 close is their relation. 



But when we come to the consideration of the free elements 

 the similarity is more apparent. The various forms of amor- 

 phous carbon, such as bone black, lamp black, charcoal, 

 coke, etc., have their counterpart in amorphous silicon, which 

 is usually seen as a brown powder. This powder burns in the 

 air to the dioxide. L,ike carbon, it is non-volatile and infus- 

 ible. Graphitoidal silicon is very similar in appearance to 

 graphite. It melts at a temperature between the melting 

 points of pig iron and steel (iioo°-i30o° C), but is less 

 active chemically than the amorphous variety. Graphite and 

 graphitoidal silicon bear much the same relations to their 

 amorphous varieties. A great commercial application of 

 graphite lies in the making of crucibles for melting metals, 

 notablv brass. \'essels of almost identical appearance have 



