﻿T. B. Osborne — Higher Oxides of Copper. 341 



No. 2. 



I. 



CuO 



•3035 







•3035 





BaO 



1-0754 



1-0222 



•0532 









•0242 



•0240 



•0002 



II. 



CuO 



•3127 







•3127 





BaO 



1-0837 



No. 



1-0197 

 3. 



•0640 



I. 



CuO 



•2603 







•2603 





BaO 



•5698 



•5577 



•0121 









•0082 



' -0072 



•0010 





Ci 



•0142 



•0118 



•0024 



II. 



CuO 



•1918 





•1918 





BaO 



•5627 



•5577 



•0050 









•0082 



•0064 



•0018 



The above analyses show a small amount of barium in the 

 precipitates, compared with the copper, which varies greatly 

 with the different preparations and considerably in the different 

 samples of the same preparation, while duplicate determinations 

 in the solutions agree quite closely. A little chlorine was also 

 present, but it seems more probable that the barium and chlo- 

 rine were carried down with the precipitate as barium chloride 

 than that they were united with the copper. The results show 

 a fair average of a very large number of determinations of oxy- 

 gen in various preparations. While with the calcium-copper 

 precipitates I never failed to get an oxidation of the ferrous 

 sulphate or chloride, with the barium-copper precipitates I 

 never got an oxidation greater than in No. 3, II. Ic is evident 

 that we have here two different compounds, but what the 

 barium precipitate can be I cannot even suggest. I could get 

 no evidence of an excess of oxygen in it in any way. Iodized 

 starch paper was unchanged when placed near the precipitate 

 moistened with hydrochloric acid ; whereas chlorine was freely 

 evolved when the calcium cuprate was thus treated. When 

 treated with sulphuric acid there was no evolution of oxygen, 

 while with the calcium cuprate there was always a lively evo- 

 lution of gas. When strontium was substituted for barium the 

 same changes of color took place, excepting a darker, duller 

 red precipitate was formed. It was necessary to suspend finely 

 ground crystals of strontium hydroxide in the water on account 

 of its slight solubility. 



With barium, strontium and calcium (when calcium hydrox- 

 ide solution is used instead of suspended lime) the same changes 

 of color take place, but in the case of the calcium the red pre- 

 cipitate, which is the final state with the barium and strontium 

 precipitates, is followed by a change to a bulky black precipi- 

 tate which evolves oxygen for some time and gradually settles 

 in the solution and changes to a crystalline rose-red precipitate. 



