268 British Association for the Advancement of Science. 
sulphate of lime: this second glass cylinder was filled with a solution 
of sulphate of copper; into the latter a plate of copper, furnished 
with a conducting wire, was immersed, whilst into the solution of salt 
a plate of zinc, also furnished with its conducting wire, was plunged. 
* Under these circumstances, a current of electricity is developed, the 
plate of zinc becoming positive, and the plate of copper negative, 
although the intensity of the current could be scarcely supposed 
sufficient to the production of chemical action. Mr. Bird has how- 
ever shown, that when the connecting wires of the two plates of this 
elementary battery were immersed in a saline solution of a compound 
salt, the most important physical and chemical changes were produ- 
ced; and that if, instead of immersing these wires in fluids, they are 
twisted together, so as to insure metallic connexion, it will be found 
that the electric current developed will produce most interesting and 
unexpected effects on the metallic solution present in the smaller ; 
for although, it might be anticipated that the copper would be redu- 
ced, yet we should expect that this reduction would be most obyious 
at the surface of the negative electrode, which, however, Mr. Bird 
has shown not to be the case; for on examining the plug of sulphate 
of lime, (plaster of Paris,) closing the smaller cylinder, and separa- 
ting the solution of sulphate of copper from the brine, it was found 
that beautiful and hard crystals of metallic copper were deposited in 
it, not in a confused manner, but in veins precisely resembling those 
met with in mines, of which, however, it is scarcely necessary to 
observe they presented but a miniature resemblance. From this, it 
appeared, that the mere passage of an electric current, independent 
of the presence of poles, was sufficient to effect metallic reductions, 
supporting in a satisfactory manner, the experiments of Dr. Faraday 
on this subject. ‘The metallic crystals thus obtained were very hard 
and brilliant, resembling in a striking manner those produced in the 
vast theatre of nature, indeed, some specimens exhibited by Mr. 
Bird, obtained by the aid of his miniature apparatus, precisely, and, 
indeed, so closely resembled the most perfect forms of native a 
ruby copper ore, that they would probably defy the most expert 
mineralogist to discover their true origin. These effects were, more- 
over, by no means confined to salts of copper; for, when solutions 
of antimony, lead, tin, zinc, bismuth, silver, or other metals, were 
_ placed in the inner vessels, instead of a solution of copper, the met- 
als were, in every case, reduced, partly on the plate of copper which 
served fi : ‘ : : 
or the negative electrode, but chiefly in crystals imbedded 
in the mass of plaster of Paris closing the inner cylinder. 
