1893 - 94 .] 
Dr Walker on Hydrolysis. 
259 
which the saponification proceeds is directly dependent on the actual 
concentration of sodium hydroxide in the solution. 
It should be mentioned that, although the solution of sodium 
hydrosulphide became yellow in the course of an hour when it was 
mixed with ethyl acetate, by itself it showed no tendency to become 
coloured even after a week had elapsed. 
The following numbers were obtained for the electric conductivity 
of dilute solutions of sodium hydrosulphide at 25° by Kohlrausch’s 
method. 
Dilution. 
Molecular Conductivity. 
16 
96 
32 
101 
64 
105 
128 
107 
256 
109 
512 
110 
1024 
no 
The numbers given under dilution signify the number of litres of 
solution which contain a gram-formula- weight of the dissolved sub- 
stance. The molecular conductivity is expressed on the basis of 
Siemens’ mercury unit of resistance. Ostwald has found that the 
difference between the molecular conductivity of sodium salts of 
monobasic acids, at a dilution of 1024 1. and at 32 1., is always very 
nearly equal to 10. Here we find the difference to be 110-101 = 9, 
so that in this respect sodium hydrosulphide behaves as the sodium 
salt of a monobasic acid, and gives no indication of hydrolysis taking 
place in its solutions to any marked extent. 
In the case of the so-called sodium sulphide solutions we have 
a very different state of matters. Such a solution behaves with 
respect to rate of saponification and to electrical conductivity pre- 
cisely as if it consisted of a mixture of equivalent solutions of 
sodium hydroxide and sodium hydrosulphide. When a saponifi- 
cation experiment was conducted under the same conditions as those 
given above for sodium hydrosulphide, the rapidity of the action 
was such that it could not be measured. In order to diminish the 
rate, a smaller proportion of ethyl acetate was added, and the 
numbers in the following table obtained. The indicator employed 
