120 C. H. Warren — Calcium Carbide. 



Aet. IX. — The Crystalline Characters of Calcium Car- 

 hide; by C. H. Waeeen. 



Something over ten years ago the crystalline charac- 

 ters of calcium carbide were the subject of a thorough 

 study in connection with litigation relative to certain 

 patent claims. 



The first crystallographers to study the crystalline 

 properties of carbide in detail were the late Professor A. 

 J. Moses and the writer, and they began their observa- 

 tions probably at about the same time. In 1912 Professor 

 Moses proposed, that, at a later date, lie and the writer 

 should cooperate in publishing the results of their study. 



Unfortunately the carrying out of this joint work was 

 delayed, and he who would have been senior author has, 

 to the deep sorrow of all who knew him, ceased forever 

 his scientific work. 



The crystalline properties of this substance are in 

 many ways so interesting, perhaps unique, that the writer 

 feels it desirable to put them on record, realizing, how- 

 ever, that they will doubtless lack many observations of 

 interest that Professor Moses would have contributed. 



In the course of the litigation above referred to. Pro- 

 fessors J. P. Iddings and L. V. Pirsson, E. H. Kraus and 

 Doctors F. E. Wright and H. P. Whitlock also studied 

 the carbide. 



Megascopic characters.^ — Calcium carbide as made in 

 the electric furnace is for the most part a granular or 

 columnar crystalline aggregate of a prevailing black, 

 reddish-black, or reddish-brown, less commonly, yellowish- 

 red or brown color. Natural surfaces sometimes show a 

 bluish or purplish iridescence. The crystalline structure 

 is usually revealed on broken surfaces by the presence of 

 a great number of brilliantly reflecting cleavage surfaces. 

 The cleavages are nearly equal and parallel to three direc- 

 tions at right angles to one another. The granularity of 

 carbide varies widely. In quickly chilled material from 

 the margins of ingots the grain is very fine to invisible. 

 Material taken from the inner parts of slowly cooled 

 ingots, or from carbide cooled in the furnace, may be 

 coarse grained, the individual dimensions of grains being 

 several millimeters or even a centimeter or more. 



Freshly broken cleavage surfaces when examined with a 



