﻿T. B. Osborne — Higher Oxides of Copjoer. 337 



From this he concluded that the formula of the oxide was 

 probably Cu 2 3 and further that this oxide acted as an acid 

 and was united with lime, forming a cuprate of calcium, 

 although he obtained no proof that this latter supposition was 

 correct. I repeated Crum's experiments in making this com- 

 pound of copper with the results as described by him. Hop- 

 ing to obtain a more accurate determination of the oxygen I 

 tried the following method. 



After the precipitate had settled, the hypochlorite solution 

 was poured off as far as possible and then the flask filled up 

 with lime water and shaken in order to mix thoroughly. After 

 allowing the precipitate to completely settle, 50 c. c. of the 

 clear solution were drawn off and a known amount of ferrous 

 sulphate solution run in and after standing some minutes sul- 

 phuric acid added to dissolve the precipitated ferrous and ferric 

 hydroxides and then the excess of ferrous sulphate titrated off. 

 50 c. c. of the solution containing the copper precipitate were 

 next drawn from the bottom of the flask and treated with the 

 same amount of ferrous sulphate solution in the same way. 

 The difference in the titer in the two cases represented the oxi- 

 dation due to the excess of oxygen in the copper compound. 

 The strength of the permanganate solution being known the 

 weight of oxygen was easily calculated. The first 50 c. c. of 

 clear solution drawn off were in all cases examined for copper 

 but none was found. The copper in the other 50 c. c. was 

 carefully determined and the ratio between the copper oxide 

 found and the excess of oxygen calculated. Thus I obtained 

 the following results : 



A. 



"Weight. Ratio. 



I. 



CuO = 



•1888 g 



rams. 



CuO = 2-95 





= 



•0129 



a 





= 1- 



II. 



CuO = 



•1261 



a 





CuO = 3- 





= 



•0084 



a 





= 1- 



[II. 



CuO = 



•0861 



a 





CuO = 3-25 





= 



•0053 



a 



B. 



= 1- 



"Washed thoroughly by decantation. 



I. 



CuO = 



•1524 



a 





CuO = 2-38 





= 



•0129 



a 





= 1- 



II. 



CuO = 



•3182 



(( 





CuO = 2-57 





= 



•0249 



it 



C. 



= 1- 



I. 



CuO = 



•2278 



it 





CuO = 2-83 





= 



•0162 



t< 





= 1- 



II. 



CuO = 



•0716 



it 





CuO = 2-40 





= 



•0060 



a 





= 1- 



