1897-98.] Mr W. W. Taylor on Sodium Thiosulphate. 
249 
temperatures were constant to 0T° C. Below 50° C. the solu- 
tions were in contact with bTa 2 S 2 0 3 , 5H 2 0 ; above 50° C. in 
contact with Na 2 S 2 0 3 , 2H 2 0 ; and at 50° C. solutions were pre- 
pared in contact with each of them, and found to have the same 
concentration. 
The analysis of the solutions was carried out as follows: — A 
weighed quantity of the solution was made up to a known volume, 
and portions of 10 c.c. were titrated with starch and standard 
iodine. The mean of two or more titrations was used in the calcu- 
lation. 
The following is the solubility table, expressed in grams of 
anhydrous sodium thiosulphate in 100 grams of water. 
Temperature. 
gm. Fa 2 S 2 0 3 in 100 gm. H 2 0. 
o 
ca 
o 
52*67 
12*2° 
62-64 
19-9° 
70-10 
0 
o 
CO 
84-68 
o 
102-6 
45° 
119-7 
*50° 
170-9 
50° 
169-7 
52-5° 
178-5 
55-6° 
190-1 
o 
o 
206-7 
72° 
237-8 
80*5° 
248-8 
90-5° 
254-2 
100° 
266-0 
If these values are represented graphically, the curve is seen to 
consist of two parts, which intersect at 50° C. The transition 
from Ha 2 S 2 0 3 , 5H 2 0 to hTa 2 S 2 0 3 , 2H 2 0 takes place at this tem- 
perature. It is also the melting-point of the former, the saturated 
solution at this temperature having the same composition as the 
solid. (See Diagram on next page.) 
* This solution was in contact with N’a 2 S 2 0 3 , 5H 2 0 ; and the temperature 
was raised from 45°. The next solution was in contact with Na 2 S 2 0 3 , 2H 2 0 ; 
and the temperature was lowered from 55°. 
YOL. XXII. 6/10/98. ft 
