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V. Observations on the Electro-chemical Influence of long-continued Electric Currents 
of Low Tension. By Golding Bird, F.L.S., F.G.S., Lecturer on Experimental 
Philosophy at Guy's Hospital, 8$c. Communicated by Thomas Bell, Esq., F.R.S. 
Received January 30, — Read February 2, 1837. 
1. SCARCELY any branch of scientific investigation has yielded more important 
and interesting results than electro-chemistry, which, as is well known, in the hands 
of a Davy, demonstrated the existence of the alkaline metals, and formed a memorable 
and important epoch in the history of chemical science. Sir Humphry Davy availed 
himself of the energetic influence of voltaic currents in a high state of tension, and 
elicited by means of large batteries. To M. Becquerel, however, we are almost en- 
tirely indebted for our knowledge of the chemical agency of feeble currents in reducing 
certain refractory oxides to the metallic state, although it must not be forgotten that 
Dr. Edmund Davy applied the power of weak currents of electricity to the detection 
of the metallic poisons, by reducing them to the reguline state. Bucholz appears, in 
1807, to have succeeded in obtaining crystals of metallic copper by the aid of a simple 
voltaic circle. But it is to our illustrious countryman Dr. Faraday that we owe our 
acquaintance with the interesting circumstance of the power possessed by a current 
of very low intensity (elicited by a single pair of platinum and zinc plates) in decom- 
posing several saline combinations, as the iodide of potassium, sulphate of soda, &c., 
and isolating their respective constituents. In offering the following observations, I 
have not sufficient presumption to suppose them to be possessed of any very important 
or original value ; but being, as they are, the results of carefully repeated experiments, 
and containing an account of what I believe to be some previously unobserved facts, 
I deem myself justified in submitting them to the notice of the Royal Society. 
2. The facts recently pointed out by M. Becquerel of the energetic power exerted 
by weak electric currents in effecting the reduction not only of the oxides of copper, 
lead, or tin, but even of glucina, alumina, and silica, are probably very well known 
to every one. This philosopher obtained these interesting results by means of a single 
pair of plates, placing the solution of the metallic salt in a glass tube closed at one 
end by means of a plug of moistened clay, and immersed in a weak solution of com- 
mon salt : on placing then a compound metallic arc formed of zinc and platinum in 
the solutions in such a manner that the platinum leg might be immersed in the tube 
containing the metallic solution, (to which M. Becquerel applies the general term of 
“ negative tube,”) whilst the zinc dips in the solution of salt, decomposition ensues, 
and after a lapse of time, varying from a few hours to some weeks, the metal is gene- 
