HISTORY OF ELECTRO-METALLURGY. 



19 



with P, a porous cell filled with dilute acid, in which is placed z, a 

 zinc plate, which is connected by a wire with a medal m' in the 

 second vessel charged with sul- 

 phate of copper. The medal, m, 

 in the first cell, is connected by 

 a wire to a piece of copper, c, 

 in the second cell : the electri- 

 city passes from the zinc z to m, 

 and by the wire to c, then to 

 w', and by the wire back to the 

 zinc z. 



The use of a separate battery, 

 however self-evident, was a 

 valuable addition to the electro- 

 metallurgist for many of his 

 operations ; although for some purposes the original single cell is to 

 be preferred. 



Laws of Deposition. As might have been expected in the excite- 

 ment occasioned by the announcement of a new art, every individual 

 experimenter became so engrossed by his own investigations, and 

 their results, as to overlook the labours of others, and at last to lay 

 claim to the honour of originating all the discoveries they announced. 

 We shall quote one or two instances of these absorbing claims, as 

 it is important to rectify the errors they contain, because no success- 

 ful labourer, however humble, in the field of science or art, should 

 be overlooked by his more fortunate brethren. 



Extract from SMEE'S " Electro-Metallurgy' 1 '' : 

 " 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, cop- 

 per, 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." 



That Mr. Smee discovered the laws referred to we have not the 

 slightest doubt : they were published as laws in his book, and they 

 are commonly quoted as Mr. Smee's ; nevertheless, he was not the 

 first who discovered them ; the same laws were pointed out by Mr. 

 Spencer, in his original paper just quoted, published eighteen months 

 previously to the appearance of Mr. Smee's work, as will be seen 

 from the following extracts : 

 b Laws given by Smee. Laws given ly Spencer. 



" Law I. The metals are in- " I discovered that the solidity 

 variably thrown down as a black of the metallic deposition de- 



