59 



After only a litlle SO, had been willidravvn the reaclion prodnct 

 consisted of a powdery, bnt sliglilly caked brownisli-red mass. 



JO. At 570", SCj was now constantly being withdrawn from 

 the mixture and each time the ecpiilibrium pressure was measured. 

 This remained the same until suddenly a strong depression was 

 observed. A series of points of this newly attained equilibrium was 

 determined; it is about equally sharply noticeable as the former. 

 The values return, after evacuation, again \ery exactly. The results 

 obtained are those of table V 1^^ series. 



In order to ascertain whether this last equilibrium really relates 

 to the basic sulphate Cut) . OiiSO.,. aiul hence may be re[)resented by -. 



CuO.CuSO, + Cu/) ;± 3 CuO + SO, 



it was endeavoured to obtain this sul[)liate in a pure condition. 

 WoHLER ') and others recommend heating CuSO^ at ± 800' in a 

 current of SO, ; it is then, however, mixed with a small quantity 

 of CujO. We have repeated this process, l)ut it appeared that in 

 this manner are obtained strongly caked, red masses very rich in 

 Cu,0. Consequently \Ve have abandoned this method and endeavoured 

 to obtain the compound in a pure condition by lieating CuSO^ in a 

 current of air at T'iO"^ — 740°. This gave better results; the product 

 was coloured a pure yellow and yielded on analysis 6(5. 217» CuSO, 

 (theory for CuO.CuSO,, G(3.t)27„). 



TABLE V. CuO CUSO4 + Cu,0 "^ 4 CuO + SO. (fig. 3 line V). 



1) L. WöHLER,' W. Plüddemann and P. Wöhler, Ber. der deutschen them. Ges. 41. 

 710 (1908;, 



