Mr Granam on Water as a Constituent of Salts. 303 
again have occasion to allude under sulphate of lime, a body which 
illustrates it more strikingly than the sulphate of water. 
Sulphate of Water with Sulphate of Patash : HS(KS). Bisulphate 
of Potash. 
Of all the sulphates, the acid sulphates or bisulphates of pot- 
ash and soda deviate least from the primary sulphate of water. 
We have, in the one case, merely sulphate of potash ; and, in the 
other, sulphate of soda, substituted for the saline atom of water 
of the sulphate of water. In none of the specimens of these salts 
which I had occasion to examine, was there any water of crystal- 
lization, and the evidence which is given of its occasional pre- 
sence is of a very doubtful description. The crystals could be 
heated to 300°, without impairing their transparency ; and they 
fused at a temperature not under 600°, without the loss of any 
thing, except a trace of water, which had been mechanically re- 
tained. Upon heating a bisulphate nearly to redness, a portion 
of sulphate of water is expelled. I greatly doubt whether water 
ever comes off in such a case unaccompanied by sulphuric acid, 
although Berzexius appears to be of a different opinion. It is 
well known that the sulphate of water is not entirely expelled 
from these salts by heat alone, even the most intense. Sulphate 
of water, however, leaves the sulphate of soda with greater faci- 
lity than it leaves the sulphate of potash. 
These sulphates should be crystallized from concentrated. so- 
lutions at a high temperature ; for their solutions are very apt to 
undergo decomposition at low temperatures, the neutral sulphate 
crystallizing, and leaving “ the sulphate of water with saline 
water” in solution. I have often observed this decomposition to 
occur, even in solutions containing a great excess of sulphuric 
acid. At low temperatures, therefore, the affinity of sulphate of 
water for “ saline water,” prevails over its affinity for sulphate of 
potash. Crystals of bisulphate of soda, pounded and put under 
