742 Prof. Townsend and Mr. Hurst on the 
are indebted to him for having given us some very pure 
barium hydrate. As in the previous experiments, the vessel 
containing the electrolyte was not open to the air, and was 
designed so that the hydrogen should be evolved without 
having any oxygen mixed with it. 
The leak in the apparatus used for the determination of 
conductivities did not exceed 3, of a millimetre in 24 
hours; and as a fresh supply of dry gas was used for each set 
of experiments, the pressure of the air in the apparatus at any 
time during the experiments must have been less than 
30090 Mm. This amount could not have had any appreciable 
effect on the experimental results. 
In order to test the previous results some of the experi- 
ments were repeated. At 4 mms. pressure, when a force of 
300 volts per centimetre was applied, the conductivities 
corresponding to distances between the plates of 6, 8, and 
10 mms. were found to be proportional to the numbers 
1, 2°94, and 11°9, the numbers previously obtained being 
1, 2°93, and 11°9. It is evident that if there had been any 
impurity in the gas which was used in the previous 
experiments, it did not affect the conductivities to any 
appreciable extent. 
The experiments at 8 mms. were repeated, as it was 
evident that in one case some error had been made, and there 
was one number which could not be well reconciled with a 
theoretical series of conductivities. All the numbers referring 
to that pressure which are given in the previous paper were 
verified except the number in which an error was suspected. 
This occurred in the ratio of the conductivities obtained with 
a force of 525 volts per centimetre corresponding to distances 
of 5 and 7 mms. between the plates, which was about 20 per 
cent. too large. The correct values of the conductivities at a 
pressure of 8 mms. when a force of 525 volts per centimetre 
is applied are given in the following table of results from 
experiments which were repeated several times :— 
Hydrogen, 8 mms. pressure. 
AE ts 3 ‘D. 7 8 
0 ST ae ee | £87 14-4 LS 122 
—/F9 
ramnr 7 a ee 485 | 146 58 124 
a= 927, axX=486, V=—487. 
