Instructions for the multiplication of works of art in metal, by voltaic electricity. With an introductory chapter on electro-chemical decompositions by feeble currents / By Thomas Spencer.

  • Spencer, Thomas.
Date:
1840
Catalogue details

Licence: Public Domain Mark

Credit: Instructions for the multiplication of works of art in metal, by voltaic electricity. With an introductory chapter on electro-chemical decompositions by feeble currents / By Thomas Spencer. Source: Wellcome Collection.

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    coins; one wholly covered with metallic crystals, the other on one side only. It was used under the following circumstances. When about to make the experiment, I had not a slip of copper at hand to form the negative end of my arrangement, and, as a good substitute, I took a penny and fastened it to one end of the wire, and put it, in connection with a piece of zinc, in the apparatus already described. Voltaic action took place, and the copper coin became covered with a deposition of copper in a crystalline form. But, when about to make another experiment, and being desirous of using the piece of wire used in the first instance, X pulled it off the coin to which it was attached. In doing this, a piece of the deposited copper came off with it; on examining the under portion of which, I found it contained an exact mould of a part of the head and letters of the coin as smooth and sharp, in every respect, as the original on which it was deposited. I was much struck with this at the time; but, on examination, the deposited metal was very brittle. This, and the fact that it would require a me¬ tallic nucleus to aggregate on, made me apprehensive that its future usefulness would be materially abridged; but it was reserved for future experiment, and in consequence laid aside for a time, until my attention was recalled to the subject in a subsequent experiment already detailed, by the drops of varnish on a slip of copper. Finding in that instance that the deposit would take the direction of any non-conducting mater¬ ial, and be, as it were, guided by it, I was induced to give the previous branch of the subject a second trial, because I had in the first instance supposed that the deposition would only take place continuously, and not on isolated specks of a metallic surface, as I now found it would; but the principal inducement to investigate the subject was the fact of finding that deposited copper had much more tenacity than I at first imagined. Being aware of the apparent natural law which limits metallic deposi¬ tion by voltaic electricity, excepting in the presence of a metallic body, I perceived that the uses of the process would in consequence be ex¬ tremely limited, except in the multiplication of already engraved plates, as, whatever ornament it might produce, it would only be done by adhering to the condition of a metallic mould. I accordingly determined to make an experiment on a very pro¬ minent copper medal. It was placed in a voltaic circuit, as already described, and deposited a surface of copper on one of its sides, to about the thickness of a shilling. I then proceeded to get the deposi¬ tion off. In this I experienced some difficulty, but ultimately succeeded. On examination with a lens, every line was as perfect as the coin was from which it was taken. I was then induced to use the same piece again, and let it remain, a much longer time in action, that I might have a thicker and more substantial mould, in order to test fairly the strength of the metal. It was accordingly put it again in action, and let remain until it had acquired a much thicker coating of the metallic deposition; but on attempting to remove it from the medal, I found I was unable. It had, apparently, completely adhered to it.