184 APPENDIX. [No. VIII. 



known and recorded previously ; and it forms another instance of an 

 invention of the greatest magnitude and utility to mankind, arising from 

 the most simple beginnings. 



" The next discovery, which is fully equal in value to the idea of the 

 electrotype itself, was made by Mr. Murray. He found out that non- 

 conducting substances might have metallic copper thrown down upon 

 them by previously applying black lead. Mr. Murray's process is ex- 

 tremely simple and absolutely perfect. The first application of this inven- 

 tion was made in January 1840 ; but it is to be lamented that he did not 

 further extend its application and publish his researches, for his method 

 was communicated orally, in the conversaziones of the Royal Institution, 

 and not by any paper. I lay particular stress upon the value and perfec- 

 tion of plumbago, because some have denied its applicability ; and the 

 reader will find, throughout the whole of the work, that I have extended 

 the use of the substance, to the benefit of the public and to the fame of 

 the inventor. I have made very extensive inquiries in order to ascertain 

 who really first used plumbago for this purpose, and I have the testimony 

 of several authorities that it was Mr. Murray, whose claim, therefore, to 



this invention is rendered quite indisputable 



" Up to April 1840, the single-cell apparatus was invariably used, but 

 then Mr. Mason very ingeniously devised another mode by which the 

 reduction might be effected. He used the single-cell apparatus as a 

 Daniell's battery, which he connected with another cell to reduce another 

 metal. In the second cell he used a copper positive electrode, which was 

 dissolved during the action. By this means he made two metals by one 

 pound of zinc, or, in other words, obtained two equivalents of copper for 

 one of zinc. 



" In the ' London Journal ' for April 1840, as far as I know, is contained 

 the first specimen of printing from an electrotype, by Newton. It is a 

 small rough sketch, but as the first of the kind is peculiarly interesting* 



" The laws regulating the reduction of all metals in different states 

 were first given in this work, as the result of my own discoveries. By 

 these we can throw down gold, silver, platinum, palladium, copper, iron, 

 and almost all other metals in three states ; namely, as a black powder, as 

 a crystalline deposit, or as a flexible plate. These laws appear to me 

 at once to raise the isolated facts known as the electrotype into a science, 

 and to add electro-metallurgy as an auxiliary to the noble arts of this 

 country. 



" The regulation of the power of the battery to the strength of the 

 metallic solution also required an investigation of the principles which 

 regulated the diffusion of the newly-formed salt, which is of great 

 importance to the operator. In this work I have also appended data 

 whereby the manufacturer may calculate the expense of particular 

 processes before he adopts them. The formulae for ascertaining the 

 work that would be performed by a galvanic battery, under different 

 circumstances, cannot fail to be of great utility to the workman, if he 

 rightly employ them ; and the intimate rationale of the motion of 

 electricity in the battery must be a subject, at least, of great interest to 

 all. The principle regulating the adhesion of the reduced metal is also 

 one of paramount importance in all cases where it has to be removed from 

 the plates on which it is deposited. 



