838 Mr. Graham on the Heut disengaged in Combinations, 
with the fully hydrated sulphate of water in a crystalline form, 
and cannot therefore estimate its heat of liquefaction, 
4. Protosulphate of Iron.—Of the crystallized salt contain- 
ing seven atoms of water, the equivalent quantity, 86°39 grains, 
dissolved in 1000 grains of water in two experiments with a 
fall of 1° and 1°04. Allowing for the 39°38 grains of water 
introduced by the salt in addition to the thousand grains em- 
ployed, these results become 1°°04 and 1°08, of which the 
mean is 1°06. 
Fall on the solution of Fe O, SO, + 7 HO...1°06. 
The protohydrate of sulphate of iron, formed by drying 
the crystallized salt in air at a temperature approaching 400°, 
was found to be nearly insoluble in cold water. The anhy- 
drous sulphate was more soluble, but not sufficiently so for 
the determination of its thermal relations. 
5. Protosulphate of Manganese.—The crystallized salt em- 
ployed contained five atoms of water. The equivalent quan- 
tity, 75°47 grains, of the crystallized salt was dissolved in 972 
grains of water at 59° Fahr., with a fall of temperature in two 
experiments of 0°11 and 0°13 R., of which the mean is 0°12, 
Of the same salt made anhydrous by heat, the equivalent 
quantity, 47°35 grains, was dissolved in 1000 grains of water 
at 60° Fahr., with a rise in two experiments of 3°20 and 
3°24 R.; mean rise 3°*22, 
Rise on solution of MnO,SQ,; . . . . 3°22 
Fall on solution of MnO, SO,+5HO, 012 
Whole heat disengaged by Mn O,SO; . 3°.34 
The crystallized salt being well dried at a temperature not 
exceeding 400° Fahr., was found to retain a quantity of water 
in combination, which slightly exceeded a single equivalent, 
namely in the proportion of 5°82 grains to 5°62 grains, in 
52°97 grains of the baelratee salt, ‘The heat evolved in the 
solution of the equivalent quantity, 52°97 grains, of this pro- 
tohydrate by 1000 grains of water was in two experiments 
1°80 and 1°78, of which the mean is 1°°79. 
Rise on solution of MnO, SO;,HO .. 1°79 
Fall on solution of MnO,SO,+5HO., 0712 
1°91 
It follows that the heat evolved by the combination of the 
first atom of water with sulphate of manganese is 3°°34—1°91 
= 1%43, This result approaches to 1°47, the heat evolved 
by the combination of the first atom of water with sulphate of 
copper. The small depression of temperature produced by 
the solution of crystallized protosulphate of manganese is re- 
