330 ORIGIN AND DEVELOPMENT OF OKE-DEPOSITS. 



in 1830, were continued at intervals by himself and his assistants* 

 until the year 1842, in the following mines among others, Wheal 

 Eose (lead), Wheal Friendship (copper), Wheal Betsy (copper), 

 Pennance (lead), Lagylass (lead), Frongoch (lead), South Mold 

 (lead). Miller (lead), — the last our in Flintshire, — Coldberry 

 and Skeers (lead), Durham, &c. At Pennance Mine, near 

 Falmouth, in 1842, he found the natural currents were sufS- 

 ciently strong to magnetise iron, decompose iodide of potassium, 

 force sulphate of copper through clay in a U tube, change 

 yellow copper ore to gray ore and oxide of iron, and deposit 

 copper on an electrotype plate. In these experiments the 

 deflection of the needles were observed to continue steadily 

 in the same direction for eight months, from the south vein 

 towards the north, even when the mine was full of water. f 



By the continous action of a weak voltaic current, Mr. Fox 

 produced a little later a well-defined lamination structure in a 

 mass of well-kneaded clay placed between two metallic plates, 

 one of copper, the other of zinc, the plates being connected by 

 a wire, and electrically excited by a solution of common salt.| 



He also produced in the clay by this method a veritable series 

 of mineral veins, containing veinlets and pockets of red oxide 

 and green carbonate of copper, and brown oxide of iron, 

 and also a distinct vein of oxide of zinc. Some of these 

 metalliferous deposits were "so hard and firm as to admit 

 of being taken out of the clay in plates the size of a shilling. 



*One of these was Mr.W. Jory Henwood,F.R.S. ,the President of this Institution 

 in the year 1871. Mr. Heuwood in subsequent independent experiments came to 

 conclusions differing considerably from those of Mr. Fox, but his experiments 

 were vitiated by a disregard of some essential precautions, as Mr. Fox did not 

 fail to point out. 



fThese experiments on the electric currents in metalliferous veins were 

 afterwards repeated by Prof. Eeich of Freiberg, at the famous Himmelfahrt 

 Mine, and confirmed in all essentials, although his interpretation of the results 

 led him to attribute the phenomena altogether to the hydrothermal action within 

 the veins, and not at ail to the general earth-currents, which were considered as 

 largely effective by Mr. Fox. 



JThese experiments on the production of schistosity by electrical means were 

 afterwards repeated by Mr. Eobert Hunt, with pretty similar results (See Mem. 

 Geol. Survey, i, 433, 1846.) Mr. Henwood remarks (Trans. Boy. Geol. Soc, 

 Corn , v) that he and Mr. Sturgeon had failed in the experiment and suggests that 

 the clay was not well-kneaded. But Mr. Fox was far too careful an experimenter 

 to be so misled. 



