176 MR. CHARLES A. BURGHABDT ON THE 



sides of the tube, a small quantity of violet-red crystalline 

 cuprite was undoubtedly also present, but disappeared on 

 the experiment being continued. I dissolved the red 

 deposit in nitric acid, and detected the presence of a large 

 quantity of chlorine in the solution, also that of copper. 

 Therefore I conclude that this red substance is the so-called 

 cuprous oxychloride described by Wohler (Ann. Chem. 

 Pharm. cxxx. 376) . On exposing the substance to the air, 

 it takes up oxygen and acquires a beautiful apple-green 

 colour, becoming a cupric oxychloride which has probably 

 the same composition as atacamite. 



Chalcotrichite. — Being desirous of ascertaining what the 

 action of a moderately strong solution of sodium chloride 

 in water would be upon pure artificially prepared cuprous 

 oxide when heated with it in a sealed tube, I employed 

 the following method, viz. : — The tube was heated in an air- 

 bath for five days atatemperature varying from 150°— 180°, 

 when small traces of a green substance (probably atacamite) 

 were observed, the cuprous oxide had become dark brown 

 in colour, and on the sides of the tube there were small 

 beautiful radiating tufts of an orange-red-coloured substance 

 closely resembling the prismatic variety of cuprite called 

 chalcotrichite. Continuing to heat the tube, on the eigh- 

 teenth day it was opened, when it was found that no 

 further formation of the prismatic substance had taken 

 place, but there was a beautiful deposit of highly crystalline 

 violet-red-coloured cuprite on the sides of the tube. The 

 fibrous substance was dissolved in nitric acid (after having 

 been boiled in distilled water for several hours and carefully 

 washed) and tested for chlorine, which was found to be 

 entirely absent, whilst cojDper was present in large amount : 

 hence there can be no doubt that this prismatic substance 

 was the rare mineral chalcotrichite. From this experiment 

 it is evident that cuprous chloride was formed at first by 



