HISTORY OF ELECTRO-METALLURGY. 9 



discovery, independent of each other, excepting the announcement 

 made by one having hastened the publication of the observations of 

 the others. 



The following is Mr. Spencer's original paper on electro-metal- 

 lurgy, which we give at length, trusting that its importance in con- 

 nection with the history of the art, and the lucid description of its 

 practice, will serve as a sufficient apology for not abridging it : 



" ON WORKING IN METAL BY VOLTAIC ELECTRICITY, REPRINTED 

 PROM THE PAPER PUBLISHED BY THE LIVERPOOL POLYTECHNIC 

 SOCIETY, AND READ AT THE MEETING OF SEPTEMBER THE 12ra, 

 1830, NOTICE BEING GIVEN MAY THE STH : HENRY BOOTH, ESQ., 

 PRESIDENT, IN THE CHAIR : 



" In the paper that I have the honour to lay before the society, I 

 do not profess to have brought forward a perfect invention. My 

 only object is to point out a means by which, I hope, practical men 

 may be enabled to apply a great and universal principle of Nature to 

 the useful and ornamental purposes of life. In this, I may be con- 

 sidered sanguine, an error, I am aware, too often fallen into by 

 those who, like myself, imagine they have discovered a useful appli- 

 cation of an important principle ; but however this may fall out, I 

 shall lay an account of its results, with specimens, successful and 

 unsuccessful, before the members and the public, previously stat- 

 ing, however, that all my first experiments were made on a small 

 scale a method of procedure attended with many advantages to 

 the experimentalist himself, but having its disadvantage when laid 

 before the public. In this first respect, perhaps, the chemical experi- 

 menter has an advantage over the mechanical one, as the success of 

 his experiment, when tried on a small scale, doubly guarantees it, if 

 conducted on a still larger scale : with mechanical results I believe in 

 most instances it is the reverse. But when the chemist produces his 

 microscopic proofs, the pub He are generally slow to believe that 

 such minute appearances should warrant him in coming to any 

 general conclusion. 



"In the latter part of September, 1837, I was induced to make 

 some electro-chemical experiments, with single pairs of plates, con- 

 sisting of small pieces of zinc and equal-sized pieces of copper, con- 

 nected together with wires of the latter metal. It was intended that 

 the action should be slow : the fluids in which the metallic electrodes 

 were immersed were in consequence separated by thin discs of plaster 

 of Paris. In one cell thus formed was placed sulphate of copper in 

 solution in the other, a weak solution of common salt. I need 

 scarcely add that the copper electrode was placed in the cupreous 

 solution, the other being in that of the salt. I mention these experi- 



