Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/417

 Rh

The total quantity of all metals known to exist near the surface of the Earth (excepting Iron,) being comparatively small, and their value to mankind being of the highest order, as the main instruments by the aid of which he emerges from the savage state, it was of the utmost importance, that they should be disposed in a manner that would render them accessible by his industry; and this object is admirably attained through the machinery of metallic veins.

Had large quantities of metals existed throughout Rocks of all formations, they might have been noxious to vegetation; had small quantities been disseminated through the Body of the Strata, they would never have repaid the cost of separation from the matrix. These inconveniences are obviated by the actual arrangement, under which these rare substances are occasionally collected together in the natural Magazines afforded by metallic veins.

In my Inaugural Lecture (page 12) I have spoken of the evidences of design and benevolent contrivance, .which are apparent in the original formation and disposition of the repositories of minerals; in the relative quantities in which they are distributed; in the provisions that are made to render them accessible, at a certain expense of human skill and industry, and at the same time secure from wanton destruction,

other, the presence of a third body, which is either a conductor of electricity, or in which capillary action supplies the place of conductibility opens a path to the electricity resulting from the chemical action, and a voltaic current is formed which serves to augment the energy of the chemical action of the two bodies. In ordinary chemical actions, combinations are affected by the direct reaction of bodies on each other, by which all their constituents simultaneously concur to the general effect; but in the mode considered by Becquerel the bodies in the nascent state, and excessively feeble forces, are employed by which the molecules are produced, as it were, one by one, and are disposed to assume regular forms, even when they are insoluble, because the number of the molecules cannot occasion any disturbance in their arrangement. By the application of these principles, that is, by the long-continued action of very feeble electrical currents, this author has shown that many crystallized bodies, hitherto found only in nature, may be artificially obtained."