﻿T. B. Osborne — Higher Oxides of Copper. 335 



VII. 



Yellow brown CuO 



•2018 



1-66 









•02457 



r 



VIII. 



Brown (yellow tinge) CuO 



•2847 



1-48 









•03893 



1- 



IX. 



Brown CuO 



•2813 



1-2 









•04669 



r 



From these analyses I concluded that the green precipitates 

 were simply mixtures of the yellow with the blue and that the 

 yellow was a mixture of the brown and the green, the reddish 

 brown color of the dioxide of copper being complementary to 

 the green and thus destroying one another and leaving the yel- 

 low predominant. That these different colors are mixtures of 

 Cu0 2 , H 2 and Ou(OII) 3 was further supported by the fact that 

 I could reproduce any shade of color by mixing at any temper- 

 ature the brown Cu0 2 , H 2 with Cu(OH) 2 in proper propor- 

 tions. Furthermore the fact that all yielded hydrogen dioxide 

 when dissolved in dilute acids without evolution of oxygen is 

 evidence in support of this view. 



I found further that I could filter, wash and dry these pre- 

 cipitates under the same conditions that Kriiss employed for 

 Cu0 2 , H 2 0; and analysis by heating in a tube and weighing 

 the water and copper oxide gave results similar to those ob- 

 tained by determining the hydrogen dioxide set free by acids, 

 as is seen by I which was determined in this way while II 

 was obtained by the permanganate method. I did not find 

 that any of these precipitates decomposed at low temperatures 

 when free from hydrogen dioxide. Kriiss states that the brown 

 precipitates begin to decompose above +6° C. and the green 

 above +12° C. I found that when hydrogen dioxide was present 

 there was a slow evolution of oxygen even below +5° C. which 

 increased as the temperature rose. The precipitate however 

 underwent no apparent change until boiled for a moment or 

 two, when it suddenly yielded a large amount of oxygen and 

 black CuO separated out. It would appear then that the de- 

 composition below 100° C. is of the hydrogen dioxide, brought 

 about by the action of the copper dioxide. 



From the fact that no definite composition can be assigned 

 to any of these various colored precipitates except the blue 

 copper hydroxide and the brown copper dioxide, that they all 

 yield hydrogen dioxide with acids, that they show the same 

 behavior on heating, that the different colors can be produced 

 by different amounts of hydrogen dioxide with the same 

 amount of copper hydroxide and that the colors may be repro- 

 duced by mixing the copper hydroxide and the copper diox- 

 ide, it seems reasonable to conclude that hydrogen dioxide 

 forms but one higher oxide with copper. 



Further the yellow oxide obtained by Kriiss by fusing cop- 



