﻿I. 



CuO = 



•168V 





= 



•0117 



II. 



CuO = 



•1614 





= 



•0113 



III. 



CuO = 



•0703 





= 



•0059 



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



III. CuO = -1505 grams. CuO = 2'25 



O = -0135 " O — l- 



IV. CuO = -1217 " CuO = 2-7 



O = -0092 " O = r 



D. 

 Ferrous chloride was substituted for ferrous sulphate with re- 

 sults as follows : 



Weight. Katio. 



,ms. CuO = 2-93 



0=1- 



' CuO = 2*90 



= 1- 



CuO = 2- 



= v 



To what the irregularities in the results were due I am un- 

 able to say. The action of the hypochlorite solution on the 

 ferrous sulphate solution was the same when equal quantities 

 were used. No hydrogen dioxide could be found in the acidi- 

 fied solutions which could act on the iron irregularly and also 

 on the permanganate, and no oxygen escaped on acidifying. I 

 think it probable that a more extended trial of this method 

 would yield satisfactory results. 



I tried to use potassium iodide instead of ferrous sulphate 

 but with little promise of success as the results varied greatly. 

 I found it exceedingly difficult to obtain constant results with 

 potassium iodide in determining cupric salts alone except in 

 very dilute solutions so I abandoned this method as unreliable. 



Of course it would be impossible to prove whether calcium 

 was a constituent of this copper precipitate or not when made 

 according to Crum's method, for the suspended calcium hydrox- 

 ide settles down with the precipitate containing copper and 

 could not be separated. I found, however, that a large excess 

 of lime water could be substituted for the suspended calcium 

 hydroxide. By filtering the cold calcium hypochlorite solution 

 carefully into a large flask provided with a rubber stopper, 

 with two holes, through one of which the funnel passed and 

 through the other a tube filled with broken stick potash to 

 exclude carbonic acid, and then running in about one liter of 

 cold lime water, and adding the copper nitrate solution, the 

 copper hydroxide which first precipitated, in four or five min- 

 utes went into a perfectly clear solution of a deep blue color. 

 This solution soon changed to a green and then became nearly 

 black, and from this a precipitate began to separate which had 

 a crimson color by transmitted light, and appeared exactly like 

 the precipitate obtained with barium hypochlorite instead of 

 calcium to be described beyond. In a few minutes this pre- 

 cipitate began to evolve oxygen and was converted into a 

 heavy flocculent black precipitate. 



