346 Mr Conne tu on the Action of 
chlorine by a secondary action. When the saline solution was 
positive and the water negative no oxygen was evolved, but it 
was employed in causing the secondary appearance of chlorine 
which was observed at a far earlier period than when the reverse 
arrangement was adopted. 
When water acidulated with sulphuric acid was substituted 
for pure water, and used for moistening the asbestus, the effects 
were much more marked. The saline solution was made posi- 
tive, and the acidulated water negative ; there was effervescence 
from both poles, but no smell of chlorine, or bleaching action in 
thirteen or fourteen minutes. The battery was then reversed, 
when a distinct smell of chlorine was observed in less than one 
minute, with slight effervescence from the positive pole and 
stronger from the negative, and in a few minutes more, test- 
paper was bleached in the neighbourhood of the positive foil. 
A rather weak solution of iodide of potassium was then ren- 
dered negative, and distilled water positive, the connexion being 
made by asbestus moistened with water. A slight effervescence 
ensued from both poles. In half an hour there was not the 
slightest discoloration of the liquid in either tube. The battery 
was then reversed. Instantly the liquid near the positive foil in 
the saline solution was discoloured, without any evolution of gas 
from that pole, whilst gas appeared from the negative foil. The 
iodine gradually increased in the positive liquid. 
These results were quite analogous to those with chloride of 
potassium. When the solution of the iodide was negative, and 
the water positive, no iodine appeared, but gas was evolved from 
each pole by the decomposition of water. On the reversal of the 
battery the oxygen ceased to come, and iodine appeared in its 
place by its secondary action. 
The question with what substance the oxygen combines to 
cause the separation of the chlorine and iodine, depends on the 
point whether chlorides and iodides are dissolved as such, or as 
muriates and hydriodates. If in the former state, then the 
