306 Mr Granam on Water as a Constituent of Salts. 
Sulphate of water with sulphate 
of potash, 
Sulphate of zinc with saline water, Sulphate of zinc with sulphate of potash. 
yield | Sulphate of water with saline water. 
In the sulphate of zine and potash, the whole six atoms of 
water are retained with considerably greater force than in the 
sulphate of zinc itself; but even the double salt becomes anhy- 
drous at 250°, and, indeed, the water retained falls below a single 
atomic proportion, when the salt is dried in vacuo over sulphuric 
acid, at a temperature not exceeding 78° Fahrenheit. The sul- 
phate of potash in the double salt has not the effect of neutral- 
izing the acid reaction of sulphate of zinc, according to my ob- 
servations ; nor has it that effect in the case of any other double 
salt. 
I subjoin a table of observations, made on the quantity of 
water retained by this double salt, in different circumstances. 
In the first two columns, the composition of the quantities ac- 
tually examined is stated in grains. 
Anhydrous! Water. |Anbydrous| Water. 
Dried in vacuo over eulphus acid 
for ten days, temp. from 68° wo 17.2 0.68 100 3.95 
18°, § : ; , : 
Nine hours, at 238°, P - 19.03 1.33 100 6.99 
Two hours at 250°, and one hour 
oe imndiane aie i 7.79 | 0. 100 | 0. 
Four hours, at 250°, = Sa 6.55 0. 100 0. 
Composition of sulphate of zinc and 
potash with one atom water (by 100 5.37 
theory), : : 
Sulphate of Zine with Sulphate of Soda : ZnS( NS)-+H*. Sulphate 
of Zinc and Soda. 
This salt, I believe, has not hitherto been described. I fail- 
ed in attempting to form it, by dissolving together sulphate of 
