536 



from this it is apparent that six of these surfaces are side-surfaces 

 and that one is a middle-surface. 



aklmb is the saturationsurface of the Cu SO^. SH^O 



cbmnd „ ,, „ ,, ,, Cu Cl^. 2H2O 



chioe „ „ „ „ „ CiiCi,. 2KC1. 2H,0 



^opgf „ „ „ „ „ KCl 



gPq^^'' yy '» " " » K2 SO, 



iqlk „ „ „ „ „ Cu SO4. Kg SO4.6H2O 



pqlmno „ „ „ „ „ D 



In order to get a better view, in the figure is indicated on each satura- 

 tionsurface the solid substance, with which the solutions are saturated. 

 For the sake of abbreviation we have called Cu SO,. ÖH^O = Cu^, 

 Cu CI,. 2H,0 = Ou„ Cu CI,. 2KC1. 2H,0 = D,.,., and Cu SO,. K, SO,. 

 6H,0=:D,.,.,. 



The middle-surface p q Im n is the saturationsurface of a salt, which 

 we have represented by D. In order to find the composition of this 

 salt we have applied the rest-method, viz. the analysis of the solution 

 and the corresponding rest. From numerous definitions it follows 

 that this salt has the composition : 



Cu SO,. K, CI, = K, SO,. Cu CI, = D. 

 or Cu SO,. K, CI, H,0 = K, SO,. Cu CI,. H,0 = Dx 



Some determinations pointed viz. to Da. others to D^, again others 

 to a mixture of D^ and Dx, so that in the region pqJmno (fig. 1) 

 perhaps the two salts D^ and Dx occur. 



The probability that more than one solid salt occurs in this region, 

 is enhanced by the following observations. In some cases the solid 

 substance was precipitated after shaking (which lasted sometimes a 

 month or longer) within some hours as a greenish powder, in other 

 cases there was formed a greenish or blue-greenish paste, which 

 after days did not yet settle, but stui*k to the sides of the shake- 

 bottle. In the first case we could easily remove a large part of the 

 mother-substance by suction, in the latter case this appeared practi- 

 cally impossible. F'rom all this it is apparent that in the saturation- 

 surface (fig. 1) indicated by D different salts may occur, two of which 

 have the composition Da and Dx. 



[t follows, however, from the position of the solutions saturated 

 with Da or Dx in the region of fig. 1 indicated by D, that one of 

 these salts must be metastable with respect to the other, perhaps 

 they are both metastable with respect to a third, which we have 

 however not found in our investigation. 



