injected from below, in a state of igneous fusion. A third hypothesis has been recently proposed, which refers the filling of veins to a process of Sublimation from subjacent masses of intensely heated mineral matter, into apertures and fissures of the superincumbent Rocks.[1] A fourth hypothesis considers veins to have been slowly filled by Segregation, or infiltration; sometimes into contemporaneous cracks and cavities, formed during the contraction and consolidation of the originally soft substances of the rocks themselves; and more frequently into fissures produced by the fracture and dislocation of the solid strata. Segregation of this kind may have taken place from electro-chemical agency, continued during long periods of time.[2]
- ↑ In the London and Edin. Phil. Mag. March, 1829, p. 172, Mr. Patterson has published the result of his experiments in making artificial Lead Ore (Galena) in an Earthen tube, highly heated in the middle. After causing the steam of water to pass over a quantity of Galena, placed in the hottest sport ion of this tube, the water was decomposed, and all the Galena had been sublimed from the heated part and deposited again in colder parts of the tube, in cubes which exactly resembled the original Ore. No pure Lead was formed. From this deposition of Galena, in a highly crystalline form, from its vapour in contact with steam, he draws the important conclusion, that Galena might, in some instances, have been supplied to mineral veins by sublimation from below.
Dr. Daubeny has found by a recent experiment that if steam he passed through heated Boracic Acid, it takes up and carries along with it a portion off the Acid, which per se does not sublime. This experiment illustrates the sublimation of Boracic Acid in volcanic craters.
- ↑
The observations of Mr. Fox on the electro-magnetic properties of metalliferous veins in Cornwall, (Phil. Trans. 1830, &c.) seem to throw new light upon this obscure and difficult subject. And the experiments of Ml Becquerel on the artificial production of crystallized insoluble compounds of Copper, Lead, Lime, &c. by the slow and long continued reaction and transportation of the elements of soluble compounds, (see Becquerel, Traité de l'Electricité, T. i. c. 7, page 547, 1834,) appear to explain many chemical changes that may have taken place under the influence of feeble electrical currents in the interior of the earth, and more especially in Veins.
I have been favoured by Professor Wheatstone with the following brief explanation of the experiments here quoted.
"When two bodies, one of which is liquid, react very feebly on each
