342 Mr Connex on the Action of 
or by test-paper. The battery was then reversed, the muria- 
tic acid being now connected by the same platinum foil as be- 
fore, with the positive side of the battery, and the acidulated wa- 
ter with the negative. A brisk effervescence took place as before 
from the negative pole, and a slight effervescence from the posi- 
tive, and in less than two minutes, a decided smell of chlorine was 
evolved from the positive tube, and shortly after test-paper held 
close to the positive foil was bleached, and the muriatic liquid 
got a yellow tint from dissolving chlorine. In this experiment it 
is evident that, before the reversal of the poles, no decomposition 
of muriatic acid took place, and that the whole, or greater part, 
of the oxygen which was evolved before the reversal from the po- 
sitive wire, was employed after that change in reducing muriatic 
acid by combining with its hydrogen and liberating chlorine. 
When the diluted muriatic was at once connected with the posi- 
tive pole of the battery in fresh action, and the acidulated water 
with the negative side, the smell of chlorine was even sooner, and 
more distinctly observed. 
In another experiment, I examined more particularly the gas 
evolved from the positive pole, when the muriatic acid was posi- 
tive, and found it to be chlorine. A small evaporating basin con- 
taining muriatic acid diluted with twice its bulk of water, was 
connected with another evaporating basin containing sulphuric 
acid diluted with five parts of water, by asbestus moistened with 
the latter fluid. The negative foil was placed in the dilute sul- 
phuric acid, and the positive foil brought under a tube filled with 
the dilute muriatic acid, and inverted in the basin containing the 
latter liquid. The gas evolved from the positive pole was shewn 
to be chlorine, by being gradually entirely absorbed by the li- 
quid, and by the strong smell of chlorine which the liquid ac- 
quired. 
The experiments with hydriodic acid led all to the same 
views, and, from the phenomena being more apparent to the 
senses, were even more satisfactory. 
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