28 
PROFESSOR W. A. TILDEN AND MR. W. A. SHENSTONE ON THE 
Solubility of sodium sulphate.—Melting point 860° C. 
Observer. 
Temperature. 
Anhydrous salt Na- 2 S0 4 
in 100 parts of water. 
Gat Lussac (Ann. Chim. 
o 
0 
5-02 
Phys., si., 312) 
11-6 
10-12 
13-3 
11-74 
17-9 
16-73 
25'0 
28-10 
287 
37-35 
307 
43-05 
31-8 
47-37 
327 
50-65 
Lowel (Ann. Chim. Phys. 
(33 
50-76 
[3], xlix., 42) 
(34 
55-00 
407 
48-78 
45-0 
47-81 
50-4 
46-82 
597 
45-42 
70-6 
44-35 
84-4 
42-96 
T. and S. 
100-0 
42-41 
Gat Lussac 
1031 
42-65 
T. and S. 
120 
a. 41-9 b. 42-0 
Mean 41 "95 
140 
a. 41-9 b. 42-1 
„ 42-00 
In the 
160 
a. 42-8 b. 43-0 
„ 42-90 
> metal 
180 
a. 44"2 b. 44'3 
„ 44-25 
tube. 
230 
„ 46-40 
In this table and curve (Plate 1), the results of Lowel between 33° and 34° are 
substituted for those of Gay Lussac, as being probably more correct. At 34°, or a 
fraction above, crystals of the ordinary salt with 10H 2 O melt, and, if the experiment 
be conducted with due care, without separation of anhydrous salt. Such a liquid is 
a solution of 78'8 parts of Na 3 S0 4 in 100 parts of water, and falls naturally into its 
place at the highest point of the curve. 
The solubility of sodium sulphate at 100° was determined in several ways, in order 
to ascertain whether the mode of operating had any influence on the result. 
(a.) By heating up crystals of the decahydrated salt, without addition of water, 
in a bath of constant temperature. 
( b .) By dropping crystals of the same salt into water, heated and maintained 
at 100°. 
(c.) By adding the anhydrous salt to water at 100°. 
The result was the same in each case. 
Reference to the curve will show that, as we anticipated, the solubility of sodium 
sulphate does increase again when the temperature is carried high enough. 
The peculiarities of sodium sulphate in regard to its solubility have always formed 
an interesting problem, but we venture to think its interest is enhanced by this 
