288 ON THE COMBINATIONS OF 
vitriol; 3 atoms water, in this respect corrobor- 
ating the result obtained by the Doctor. 
I now proceeded to investigate the heat disen- 
gaged when oil of vitriol is mixed with water in 
the proportions required for forming the com- 
pounds whose specific heats I had determined. 
Though it was indispensably requisite, in these 
experiments, to use the same relative propor- 
tions which Dr. Thomson used, I conceived 
that there must be an objection against using 
the same guantity of oil of vitriol in every ex- 
periment;—for, when 1000 grains by weight of 
oil of vitriol are mixed with 183.6 grains of 
water (1 atom oil of vitriol to 1 water), the re- 
sulting compound weighs 1183.6 grains, and, 
its specific gravity being 1.7837, its bulk, at the 
temperature of 60°, must be equal to 663.6 
grains of water; and when 1000 grains of oil 
of vitriol are mixed with 734.6 grains of water 
(1 atom oil of vitriol to 4 water), the compound 
weighs 1734.6 grains, and, its specific gravity 
being 1.4737, its bulk, at the temperature of 
60°, must be equal to 1177 grains of water; 
consequently, the bulk of the resulting mix- 
ture of 1 atom oil of vitriol with 4 water is 
nearly twice as great as that of 1 atom oil of 
