﻿334 



T. B. Osborne — Higher Oxides of Copper. 



and anhydrous, and suggested that it might be the same as 

 Brodie's oxide. Having been unable to find any investiga- 

 tions of the composition of these variously colored precipitates 

 I thought it worth while to try and straighten them out. I 

 found that if copper hydroxide (prepared by precipitating 

 nitrate of copper with soda and washing thoroughly with cold 

 water by decantation so as to keep the copper hydroxide in a 

 state of the finest possible subdivision) was treated with hydro- 

 gen dioxide in small amounts, a green precipitate was f. rmed 

 which by farther action of hydrogen dioxide was changed into 

 a brown. This brown precipitate was yellow by transmitted 

 light but dark brown by reflected light. When a small amount 

 was shaken up with water it appeared yellow. I found that by 

 mixing increasing amounts of hydrogen dioxide with copper 

 hydroxide the color of the precipitate varied from a yellow 

 with a greenish tinge, through yellow to brown. I made a 

 number of preparations thus varying in color and after wash- 

 ing by decantation free from hydrogen dioxide determined the 

 hydrogen dioxide set free by dissolving the precipitate, sus- 

 pended in water, with dilute sulphuric acid. By using a solu- 

 tion of potassium permanganate of known strength the hydro- 

 gen dioxide set free was easily determined, the copper in the 

 solution was precipitated with hydrogen sulphide and deter- 

 mined, and the ratio between the excess of oxygen found by 

 titration, and the copper oxide calculated. In this way I 

 found the following ratio between the oxide of copper and the 

 oxygen for the different colored precipitates with the exception 

 of I, which was determined by filtering and washing the pre- 

 cipitate with water, alcohol and ether, cooled to 0° C., drying 

 at 100° C. and then heating in a tube in a current of dry air, 

 weighing the water and copper oxide and calculating the oxy- 

 gen by difference. 



Per cent. "Weight. Ratio. 

 I. Grass green CuO 82*35 -6679 12*2 



H a O 16-29 '1322 



O 1-36 '0110 1- 









100-00 







II. 



Grass green 





CuO 



•2717 



12-7 









O 



•00422 



1- 



III. 



Yellow green 





CuO 



•3040 



7'5 









O 



•00814 



1- 



IV. 



Yellower green 





CuO 



•0701 



5-1 









O 



•00275 



1- 



V. 



Yellow (green 



tinge) 



CuO 



•4757 



4-2 













•02271 



1- 



VI. 



Yellow 





CuO 



•0633 



3-1 









O 



•00413 



1- 



