View oj M. BecquerePs Electrical Researches. 349 



the affinities brought into action, he succeeded, by electric decom- 

 position, and by subsequent recomposition of the elements, in ob- 

 taining crystals of some of the metallic sulphurets, of sulphur, of 

 the iodurets of lead and copper, of the insoluble sulphates of lime 

 and barytes, of the carbonate of lead, and other substances, a few 

 of which had previously, by other means, been obtained crystallized, 

 but of which the great majority had only been recomposed in an 

 amorphous state. In the Memoirs to which the Council have par- 

 ticularly adverted in the award of the Copley Medal to M. Bec- 

 querel, he had especially in view to explain, by the agency of elec- 

 tricity of very low tension, continued for an indefinite time, the 

 occurrence of crystallized substances in mineral veins. The suc- 

 cess with which his experiments were crowned in obtaining by 

 such means crystals of the metallic sulphurets and of other sub- 

 stances, perfectly resembling those found abundantly in mineral 

 veins, is favourable to the correctness of the views he had enter- 

 tained ; and these views derive additional support from the results 

 obtained by others, in perfect accordance with his own, by means 

 differing from those he employed, but involving precisely the same 

 principles. Mr. Fox, in his experiments, which appear to have been 

 conducted on a larger scale than those of M. Becquerel, endeavoured 

 more closely to imitate the arrangements of nature, by introducing, 

 between the substances acted on, walls of clay, in imitation of the 

 " flucan courses" in the Cornish mines ; these walls performing the 

 same functions as the moistened clay in M. Becquerel's experiments ; 

 and he infers from his results, that the pheenomena presented by the 

 mineral veins of Cornwall are explicable on principles which are 

 similar to those pointed out by M. Becquerel*. It is thus rendered 

 highly probable that the long-continued action of electricity of low 

 tension has been at least one of the means by which crystallized 

 bodies now existing in mineral veins have been produced. 



But quite independently of the bearing of M. Becquerel's results 

 on a question of great geological interest, the formation of crystals 

 of metallic sulphurets and other substances by the agency of elec- 

 tricity was a great step in chemical science. As M. Becquerel very 

 justly observes, the two branches of chemistry, analysis and syn- 

 thesis, are at present in very different states. With the exception 

 of crystals derived from aqueous solution, — which are by far the 

 least abundant of natural crystals, — and a few from fusion, the 

 great mass of crystallized bodies existing in nature had as yet re- 

 mained inimitable by chemical processes. In the Memoirs re- 

 ferred to, not only are experiments described by which crystals 

 of several of these substances have been obtained, but the principles 

 are pointed out, by the application of which we may anticipate that 

 large classes of others will be produced. M. Becquerel has thus 

 opened a new field for inquiry and discovery, in which he has him- 

 self gathered the first fruits, but which still offers to future labourers 

 the prospect of an abundant harvest of knowledge as regards both 

 the recomposition of crystallized bodies, and also the processes 

 * See Lend, and Edinb. Phil. Mag., vol. xi. p. 203. 



