Page:Proceedings of the Royal Society of London Vol 4.djvu/45

Rh 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 phenomena 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 priuciples 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 which may have been employed by nature in the production of such bodies in the mineral kingdom.

A Copley Medal has been awarded to John Frederick Daniell, Esq., for his two papers on Voltaic Combinations, published in the Philosophical Transactions for 1836.

The Council are desirous of testifying, by this award, their sense of the great value of Mr. Daniell’s invention of a new form of the voltaic battery, capable of producing, for a considerable length of time, a perfectly equal and steady current of electricity. The prin- ciples on which his apparatus, which he terms the constant battery, is constructed, were the results of a series of well-devised experi- ments, directed to the discovery of the cause of those great and often rapid variations in the power of the ordinary battery, which have hitherto limited its utility when employed for purposes of philosophical research, and the removal of which has greatly ex- tended the range and multiplied the applications of this powerful instrument of chemical analysis.

The train of reasoning that led Mr. Daniell to this discovery, originated in an inquiry which he undertook with the view of determining with precision the influence exerted by the different parts of the voltaic battery in their various forms of combination. For �