211 Hunt and Kraus — Composition of Melanochalcite. 



glass, effervescence takes place immediately, while at the same 

 time the extinguishable portion of the doubly refractive 

 material is largely removed from the area affected by the acid. 

 Under snch treatment it is but natural to infer that the car- 

 bonate, malachite, would be the first to be attacked by the 

 acid, removing this mineral from view and leaving the less 

 readily soluble tenorite and chrysocolla. 



These observations were made on the material described in 

 this paper and also on that originally investigated by Koenig. 

 In case of the latter material it should be pointed out that the 

 effervescence takes place with greater vigor, which is in accord- 

 ance with the above interpretation, inasmuch as there is a much 

 larger proportion of the carbonate constituent present. Koenig 

 thought that his material was homogeneous, but our micro- 

 scopical investigations upon material used by him did not con- 

 firm his assumption. 



It would seem, therefore, from a study of the meager data 

 at hand that melauochalcite is not a chemical compound but 

 rather a mixture of tenorite, chrysocolla, and malachite in 

 varying proportions, and as such no definite formula should be 

 assigned to it. If the term melanochalcite is to be retained in 

 mineralogical literature it must, therefore, be interpreted as 

 referring to such a mixture and not to an independent mineral 

 species as thought by Koenig when he assigned it to the 

 material described and analyzed by him. 



Mineralogical Laboratory, University of Michigan, 

 Ann Arbor, Michigan. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. The Extraction and Recovery of Radium, Uranium and 

 Vanadium from Carnotite. — Charles L. Parsons, R. B. Moore, 

 S. C. Lind and O. C. Schaefer, in a pamphlet of 124 pages, have 

 described the investigations and operations that have been carried 

 on by the National Radium Institute in cooperation Avith the 

 U. S. Bureau of Mines in connection with the treatment of the 

 carnotite ores occurring in Colorado. Dr. Howard A. Kelly of 

 Baltimore and Dr. James Douglas of New York City, who were 

 interested in the production of radium for use in two hospitals 

 with which they were closely connected, were instrumental in 

 forming the Radium Institute, and this Institute agreed to fur- 

 nish the sum of $150,000 for carrying out the work. Preliminary 

 operations were begun in March, 1914, at a plant built at Denver 

 which was enlarged about a year later. The capacity of the 



