410 RECENT PROGRESS IN PHYSICS. 



amount of aid he seems to have received, no really important result 

 has been obtained. A report in the Comptes Eendus of 1840 (Ding- 

 ler's Journal, vol. 77) sets forth in brilliant colors the advantages 

 of the new process, but^ though a great many electrical reactions are 

 described, very little information c^n be found on the subject in ques- 

 tion, except that the method has to be modified according to the nature 

 of the ores, and that a slight previous roasting is required if the ores 

 do not contain metallic silver or sulphuret of silver ; for it was to the 

 ores of this metal that his first experiments were confined, although 

 he intended to take up the other metals in their turn. Becquerel, by 

 irrelevant digressions, makes it very difficult to understand his dis- 

 cussions, and taxes the patience of the reader. 



In a later report in the Comptes Rendus of 1842, No. 4, (Dingler's 

 Journal, vol. 84,) Becquerel gives an account of his experiments in 

 separating gold. His process is as follows : The ore is dissolved in 

 muriatic acid, and another muriatic solution is prepared containing 

 all the other metals in the same proportion in which they are con- 

 tained in the ore. These two solutions are brought to the same den- 

 sity, and these serve as the exciting liquids of a simple battery, that 

 containing the gold being placed with a platinum plate in the inner 

 vessel, which has a clay stopper in its bottom, and the other in the 

 outer vessel with a copper plate. The circuit must be kept closed 

 until all the gold is deposited upon the platinum, whose increase of 

 weight indicates the quantity of gold precipitated. But it seems that 

 in the use of this process on a large scale the subsequent separation 

 of the gold from the platinum might present new difficulties, in addi- 

 tion to those which would be incurred by an imperfect exhaustion of 

 the solution of gold. 



A similar proposition had before been made by a Mr. Byer, (Ding- 

 ler's Journal, vol. 80 ; from Mechanic's Magazine, No. 911,) and its 

 priority disputed by Martin Roberts, but rather with the view of ob- 

 taining a quantitative determination of ores after their qualitative 

 analysis. The ore properly prepared was to be dissolved, and the 

 solution used in a simple battery as one of the liquids, diluted muriatic 

 or sulphuric acid being used for the other. The metals to be employed 

 should be two which are nearest alike in affinity, and the metal used 

 as the negative pole should be the same as the one to be precipitated. 

 If, for instance, iron is contained in the solution, iron and zinc must 

 be taken, a known portion of the dissolved ore put in contact with the 

 weighed iron plate and the circuit kept closed until the exhaustion 

 of the solution of iron, which metal only, it is said, will be deposited 

 upon the iron plate. If there is copper in the solution, copper and 

 iron should be used ; and in this manner different metals may succes- 

 sively be separated, and their quantity determined by the increase of 

 weight of the negative metals. 



In the Comptes Rendus of May, 1846, (Dingler's Journal, vol. 101,) 

 Becquerel indicates a process for decomposing silver ores which are 

 insoluble in water. They are placed with a solution of common salt 

 in a glass, with the indispensable clay stopper in its bottom, and this 

 is set in another glass also containing the same solution, into which 

 zinc is immersed connected with the ore by means of a silver wire. 



