16 HISTORY OF ELECTRO-METALLURGY. 



u I became now of opinion, that this latter method might be applied 

 to engraving much better than the method described in the first 

 portion of this paper. Having found in a former experiment that 

 copper in a voltaic circuit deposited itself on lead with as much ra- 

 pidity as on copper, I took a silver, coin, and put it between two 

 pieces of clean sheet-lead, and placed them under a common screw 

 press. From the softness of the lead, I had a complete and sharp 

 mould of both sides of the coin, without it sustaining injury. I then 

 took a piece of copper wire, soldered the lead to one end, and a piece 

 of zinc to the other, and put them into the voltaic arrangement I 

 have already described. I did not, in this instance, wax the mould, 

 as I felt assured that the deposited copper would easily separate from 

 the lead by the application of heat, from the different expansibility 

 of the two metals. 



" In this result I was not disappointed. When the heat of a spirit- 

 lamp was applied for a few seconds to the lead, the copper impres- 

 sion came easily off. So complete do I think this latter portion of 

 the subject, that I have no hesitation in asserting that fac-similes of 

 any coin or medal, no matter of what size, may be readily taken, 

 and as sharp as the original. To test further the capabilities of this 

 method, I took a piece of lead plate, and stamped some letters on 

 its surface to a depth sufficient to print from, when in relief. I de- 

 posited the copper on it, and found it came easily off, the letters 

 being in relief. 



" Finding from this experiment that the extreme softness of lead 

 allowed it to be impressed on by type metal, I caused a small por- 

 tion of ornamental letter-press to be set up in type, and placing it 

 on a planed piece of sheet lead, it was subjected to the action of a 

 screw press. 



" After considerable pressure, it was found that a perfectly sharp 

 mould of the whole had been obtained in the lead. A wire was 

 now soldered to it, and it was placed in an apparatus, similar in 

 principle, but larger than the one already described. At the end 

 of eight days from this tune, copper was deposited to one-eighth of 

 an inch in thickness ; it was then removed from the apparatus, and 

 the rough edges of the deposited copper being filed off, it was sub- 

 jected to heat, when the two metals began to loosen. The separa- 

 tion was completed by inserting a piece of wedge-shaped wood 

 between them. 



" I had now the satisfaction of perceiving that I had by these 

 means obtained a most perfect specimen of stereotyping in copper, 

 which had only to be mounted on a wooden block to be ready to 

 print from. 



" From the successful issue of this experiment, which was mainly 

 due to the susceptibility of the lead, I was induced to attempt to 



