262 THE AMERICAN MONTHLY [Sept., 



EDITORIAL. 



Carborundum.— This new compound is made from carbon, 

 sand and salt, but it is composed of silicon 69 per cent, carbon 

 30, im])urities 1 per cent. Under the microscope it exhibits 

 crystals of a blue color, but with some of a yellow-green color, 

 some black, and some white. The crystals are sifted through a 

 seive having 2,500 or more meshes to the square inch but are 

 too large to pass through one having 40,000 meshes to the square 

 inch. The three important characteristics of carborundum are 

 great hardness, infusibility and incombustibility. It will there- 

 fore be used much as an abrasive material and to some extent 

 replace emery. It can be used to cut diamonds. 



These crystals are rhombohedral, loth direct and inverse. 

 Proff-ssor B. W. Frazier of Lehigh, who has examined some 

 crystals, says : "A flat crystal examined under the microsco|)e 

 in converging polarized light gave the interference figure of a 

 uniaxial mineral, thus confirming the determination of hexago- 

 nal symmetry made by measurements with the goniometer." 



The Secretary of the Carborundum Comjjany, Mr. C. M. 

 Hagen, has kindly favored us with some specimens of crude 

 material. To a limited number of subscribers we can mail enougli 

 to make a few mounts, and to all our contributors who so desire 

 we shall take great i)leasure in sending samples. 



A New Illustrated Dictionary of Medicine, Biology, and 

 Collateral Sciences. — Dr. Ceorge M. Ciould has now about 

 ready an unabridged, exhaustive work of the same class, in 

 which he has already earned a reputation, and u])on which he 

 and a corps of able assistants have been uninierrui)tedly 

 engaged for several \^ears. 



The feature that will attract immediate attention is the large 

 number of fine illustrations that have been included, many of 

 which as, for instance, the series ofover fifty of the bacteria-have 

 been drawn and engraved especially for the work.' Every scien- 

 tific-minded jihysician will also be glad to have defined several 

 thousand commonly used terms in biology, chemistry, etc. 



The chief point, however, upon which the editor relies for the 

 success of his book is the unique epitomization of old and new 



