232 Passage of Electricity through Oxygen and Hydrogen. 
occasions recorded above, more molecules of water were formed 
than pairs of ions. 
Now let W, denote the number of molecules of water 
formed for the passage of each pair of ions to the electrodes. 
Then ; 
we 
dQ 
Therefore by equation (1), 
Tee ~ 
a \ = of(= ) e . © e e ° 2 
— 
o.€ . . ° . a 
where f i is the ordinate corresponding to the abscissa — 
z 
of the curve given above. 
If the force were uniform between the plates, X might be 
taken as the force, since the plates were ‘97 cm. apart. And 
then equation (2) would strongly support the view that the 
formation of water is attributable to the collisions with 
the neutral molecules of the mixed gas of the ions as they 
move to the electrodes. The simplest hypothesis would be 
that the ions by collision separate the neutral molecules of 
oxygen into uncharged atoms, and that the latter then com- 
bine with the.neutral molecules of hydrogen. 
But one is prevented from basing these views on equation 
(2), by the large and uncertain departure from uniform 
intensity which the electric force makes near the cathode. 
Moreover, the range of variation of the potential X was not 
Jarge enough to prove the validity of equation (2) except 
for a very restricted variation of X (see the tables above). 
But further experiments will shortly be made with the view 
of deciding this and other points. 
During these experiments the phenomena do not appear 
to be complicated by the effects of the heat set free by the 
chemical union of hydrogen and oxygen, although this seems 
to play such an important part at pressures of a higher order. 
The elimination of these effects at low pressure may be 
explained by the hypothesis that the energy set free by the 
formation of a molecule of water is radiated as well as con- 
ducted through the gas. For the intensity of such radiation 
would be proportional to the inverse square of the distance 
from the molecule of water, and the radiation would have 
no effect on the neighbouring molecules of oxygen and 
hydrogen unless they were within a certain distance of the 
molecule of water which was formed. When the pressure of 
the gases is reduced below some critical value, the probability 
of the reactions taking place would be extremely small. 
I wish to express my thanks to Professor Townsend who 
suggested this investigation. I am greatly indebted to him 
for his suggestions and criticisms. 
