[158] _Experiments and Observations on the Electricity of Mineral Veins_: by Robert Hunt and John Phillips; Reports of the Royal Cornwall Polytechnic Society for 1841-42. _On the Electricity of Mineral Veins_: by Mr. John Arthur Phillips; Ibid., 1843. [159] In the lead lodes of _Lagylas_ and _Frongoch_, electrical currents were detected by Mr. Fox, but none in those of _South Mold_ and _Milwr_, in Flintshire: Cornwall Geological Transactions, vol. iv. In the lead veins of _Coldberry_ and _Skeers_, in Teasdale, Durham, the currents detected were very feeble: Reports of the Bristol Association, 1838. Von Strombeck could detect no electric currents in the veins worked in the clay slate near Saint Goar, on the Rhine: Archiv. für Mineralogie, Geognosie, &c., von Dr. C. J. B Karsten, 1833. Professor Reich, however, obtained very decided results at _Frisch Glück_, _Neue Hoffnung_, _Gottlob_, and in other mineral veins in the mining districts of Saxony: Edinburgh New Philosophical Journal, vol. xxviii. 1839. The irregularities are all to be explained by the presence or absence of chemical excitation. [160] This was remarkably the case at _Huel Sparnon_, near Redruth, where the cobalt was discovered between two portions of a dislocated lode; and the same was observed by Mr. Percival Johnson in a small mine worked for nickel, near St. Austell. [161] _On the process used for obtaining artificial veins in clay_: by T. B. Jordan; Sixth Annual Report of the Royal Cornwall Polytechnic Society. See also my memoir, already referred to, in the Memoirs of the Geological Survey and Museum of Practical Geology, vol. i. [162] See Becquerel, _Traité Experimental de l’Electricité, &c. Electrical Experiments on the formation of Artificial Crystals_: by Andrew Crosse, Esq.; British Association Reports, vol. v., 1836. The lamination of clay and other substances is described in my memoir referred to, Note p. 226. [163] Report on the Geology of Cornwall, Devon, and West Somerset, by Sir Henry T. De la Beche: _Theoretical observations on the formation and filling of Mineral Veins and Common Faults_, p. 349. [164] The following analyses of waters from deep mines were made by me in 1840, and, with many others, published in the Reports of the Royal Cornwall Polytechnic Society. Consolidated Mines, Gwennap, Cornwall. In 1,000 grains of water. Muriate of soda 1·5 Sulphate of lime ·5 Sulphate of iron ·15 Sulphate of copper 1·25 Silica ·15 Alumina ·3 ---- Total 3·7