Constitution of the Sabsalls of Copper. 499 



late falls, and no copper remains in solution; by treating a 

 cold solution in the same manner; by acting on the ammo- 

 niacal sulphate by a large quantity of water, &c. Numerous 

 analyses of this salt, prepared by the various processes above 

 mentioned, have only served to confirm the correctness of 

 the formula, S0 3 4CuO, 4HO, assigned to it by Professor 

 Graham and Dr. Kane ; it is therefore useless to quote any 

 of these results. 



Dr. Kane, in the paper before mentioned, states that "this 

 salt when heated does not lose water until the temperature 

 rises above 300° Fahr., but then loses all." I find, however, 

 by exposing this salt to a temperature of 400° — 470° Fahr., 

 that it assumes a grass-green colour accompanied with the 

 evolution of water. 



When 43*2 grs. of the dingy greenish-blue powder, ob- 

 tained by digesting an equivalent of precipitated oxide of cop- 

 per with an equivalent of sulphate in the cold, were exposed 

 to the above temperature, it changed to a decided green co- 

 lour and lost 1*63 grs., this is equal to 8*9 grs. of water from 

 236, the equivalent number of the tetrasulphate of copper, 

 which indicates SO a 4CuO, 3HO as the constitution of this 

 green subsulphate. 



27*07 grs. of the blue subsulphate became of a grass-green 

 colour and lost 1*04 gr. of water, equivalent to 9*07 grs. from 

 236 grs., and indicating the formula SO a 4CuO, 3 HO as 

 the constitution of this green subsulphate, arising from the 

 loss of an equivalent of water by the blue subsulphate, SQ 3 

 4CuO, 4 HO. This green salt on analysis gave from 13*43 

 grs. 9*4 grs. of black oxide of copper, and 6*05 grs. of sulphate 

 barytes from 1 1*62 grs., proving its composition to be as above 

 stated, S0 3 4CuO, 3HO, or, 



This salt is similar to that analysed by Brunner, obtained 

 by boiling equivalents of sulphate of copper and sulphate of 

 potash together, until after repeated washings and boiling no 

 sulphuric acid could be detected in the solution. 



When this green salt is moistened, or even boiled with 

 water, it does not change colour, nor re-combine with the 

 equivalent of water it had lost, as I had anticipated from the 

 statement of Dr. Kane, that " at a temperature above 300° it 

 loses all its water, and the brown powder, if exposed to the 

 air, re-absorbs water slowly ; if moistened it combines with 



2K2 



