THE ELECTROLYSIS OF WATER. 95 
less than with polished platinum: and the latter, 
again, is exceeded in this respect when the elec- 
trode evolving hydrogen is of amalgamated zinc. 
Now in all the experiments with dilute acid, the 
chemical effects were exactly the same, consist- 
ing of the separation of the gaseous elements of 
water, and the transfer of quarter* of an equiva- 
lent of sulphuric acid from the negative to the 
positive electrode: and in the experiment with 
solution of potassa, the same gases were evolved, 
accompanied, according to Prof. Daniell, by the 
transfer of the fifth part of an equivalent of alkali 
from the positive to the negative electrode, which 
could not fail to require nearly the same intensity 
as the transfer of acid in the contrary direction. 
It is quite evident then, that the resistances of 
column 5 are not entirely due to chemical chan- 
ges ; though I have no doubt whatever that they 
arise from the joint action of chemical change and 
chemical repulsion ; a repulsion which is princi- 
pally owing to the presence of electro-positive 
materials on the negative electrode. If the re- 
sistance to electrolysis which is over and above 
* Daniell, Phil. Trans. 1840, Part 1, p. 214. I have myself 
made some rough experiments confirmatory of this remarka- 
ble fact. 
oO 
