SOLUBILITY OF SALTS IN WATER AT HIGH TEMPERATURES. 
35 
Barium acetate, Ba(C 2 H 3 0 !2 ) 3 .—Melting point of the anhydrous salt about 450°. 
Temperature. 
Anhydrous salt dissolved by 100 parts of 
water. 
O 
22 
48-5 
40 
76-5 
60 
79-0 
110 
79-3 1 
130 
85 - 6 > in glass tube. 
136 
91-9 J 
180 
141'6 in metal tube. 
(See Plate 2.) 
This salt was examined chiefly because it had been represented as an example of 
solubility diminishing with rise of temperature. When these results are plotted out 
the curve does suggest a change of this kind, and it is possible that acetate of barium 
may resemble sulphate of sodium and sulphate of calcium in parting with its water 
of crystallisation when the solution is heated. It is known to yield crystals containing 
one molecule of water of crystallisation when deposited from a warm solution, or three 
molecules of water when crystallised by cooling a weaker solution. It is probable that 
the peculiarities of its solubility are connected with the fusibility of these hydrates 
respectively. 
Calcium Hydrate. 
This compound is known to be less soluble in hot water than in cold water. We 
have made some experiments at temperatures above 100°, but as the solution seemed 
to attack the metal, and the quantity of liquid we could operate upon is but small, 
the results are of no quantitative value. 
Summary. 
Altogether we have examined sixteen salts, whereof three, namely, barium chloride, 
copper sulphate, and calcium hydrate, gave no results at high temperatures for 
reasons already given. Barium acetate presents anomalies which cannot be explained 
without further inquiry. Sodium sulphate and calcium sulphate are salts which 
certainly exist in solution in two forms, that is, in chemical combination with water 
and in the anhydrous state. 
The remaining ten salts, with one exception, barium chlorate, form crystals which, 
when deposited from solution at any ordinary temperatures, contain no water of 
crystallisation. 
It is almost fair to infer, though of course it is not certain, that these salts do not 
combine with water when the temperature is raised, and therefore when in solution at 
high temperatures exist there in the anhydrous state. 
E 2 
