182 APPENDIX. [No. VIII. 



The book commeuces with a brief but lucid exposition of galvanism, 

 and then proceeds to describe the most approved batteries, concluding 

 with a general view of the one invented by himself, which has been 

 employed by him in all the processes of electro-metallurgy. The second 

 part of Electro-Metallurgy treats of the apparatus to be employed for the 

 reduction of the metals ; of the substances capable of receiving the metallic 

 deposit ; and of the laws regulating the reduction of the metals. 



Although the laws which regulate the deposit of every metal appear 

 to be the same, and although they are very simple, yet they cost Mr. Smee 

 much labour for their development. He states them as follows : — 



Lam 1. — The metals are invariably thrown down as a black powder, 

 when the current of electricity is so strong in relation to the strength of 

 the solution, that hydrogen is evolved from the negative plate of the 

 decomposition cell. 



Law 2. — Every metal is thrown down in a crystalline state, when 

 there is no evolution of gas from the negative plate, or no tendency 

 thereto. 



Law 3. — Metals are reduced in the reguliue state when the quantity 

 of electricity in relation to the strength of the solution is insufficient to 

 cause the production of hydrogen on the negative plate in the decomposi- 

 tion trough, and yet the quantity of electricity very nearly suffices to 

 induce that phenomenon. For further information on the reduction of 

 metals I refer the reader to the paper read before the Royal Society, 

 9th of March, 1843, at page 188. 



The third part of Electro-Metallurgy treats of electro-gilding, electro- 

 plating, &c. ; of coppering non-metaUic substances, medallions, fruit, 

 vegetables, baskets, earthenware, &c. 



In the fourth part we learn the various applications of the I'eduction 

 of metals by galvanism : as the multipKcation of coins and medals ; of 

 copying seals ; of plaster casts, &c. ; of the multiplication of brasses ; of 

 making dies from embossed surfaces ; of the manufacture of moulds from 

 fruits, vegetables, &c. ; of the application of electro-metallurgy to sculp- 

 ture and other purposes. 



Part the fifth treats of the electrotype : as the multiplication of 

 type ; of plain copper-plates ; of copying engraved copper-plates ; of the 

 multiplication of steel plates ; of woodcuts ; of the daguerreotype. 



The sixth and last part of this work treats of galvanic etching. 



Such is the plan of Smee's 'Elements of Electro-Metallurgy.' In 

 order to show more thoroughly how and to what extent the author of this 

 work contributed towards the discoveries which led to the application of 

 this science not only in this country but throughout the civilized world, 

 I here transcribe its history as it is given in every edition of Smee's 

 ' Elements of Electro-MetaUurgy.' 



" We have not," he says, " to extend our inquii-y into remote periods 

 to trace the history of the arts of working in metals by the galvanic fluid, 

 for tiruly it may be said that this art belongs to our own time, and is a 

 characteristic of the present age. Whilst, however, we pursue our investi- 

 gations into the history of this subject, we find that it has had by no 

 means a sudden origin : for, at different periods, various persons have, by 

 degrees, worked out one fact after another, till the comprehensive science 

 has been developed. Electro-Metallurgy may be said to have had its 



