OEIGm AND DEVELOPMENT OF OEE-DEPOSITS. 331 



Mr. Fox's observations and experiments were fully described 

 in the scientific journals of the day, and attracted a great 

 deal of attention among all students of mineral phenomena, 

 since they assisted greatly in upsetting the Huttonian hypothesis 

 that such veins were igneous injections.'* 



As the part played by electric currents in the formation of 

 ore deposits has not received very much attention now for many 

 years, it may be well to give here a short recapitulation of a very 

 important paper which Mr. Fox prepared in 1836.f 



1. That admitting the origin of mineral veins to have been 

 derived from fissures in the earth, there is reason to believe that 

 the latter may have been produced by different causes, and at 

 various intervals ; also that many of them have been enlarged 

 from time to time. 



2. That the accumulation of mineral deposits in such 

 fissures has been likewise progressive ; and that the evidences 

 afforded by the resemblance of the vein stones to the several 

 enclosing rocks, and the arrangements and subdivisions of the 

 contents of the veins, are decidedly in favour of both these 

 conclusions ; independently of other arguments, based on 

 mechanical principles. 



3. That the phenomena of veins seem to indicate that many 

 ot the fissures penetrated to a great depth, and into regions of 

 a very high temperature ; and that, consequently, the water which 

 they contained must have circulated upwards and downwards 

 with greater or less rapidity. 



4. That since the solvent power of water seems to increase 

 in some ratio to the augmention of its temperature, it is obvious 

 that it would tend to dissolve some substances at a great depth, 

 which it would deposit, more or less, in the course of its ascent 

 through cooler portions of water ; and also in consequence of its 

 partial evaporation on reaching the surface. 



* For a fairly complete account of Mr. Fox's scientific work with references 

 to his published papers, see " A Catalogue of the Works of fiobert Were Fox, 

 F.E.S., with Notes and Extracts" by J. H. Collins, F.G.S., Truro, Lake & Lake, 

 1878, where will be found plates illustrating' the above-described experiment with 

 others bearing on the origin of metalliferous veins. 



fit appeared in the Report Roy. Corn. Pol. Soc. for that year, and was sub- 

 sequently reprinted in a separate form, but is now very scarce. 



