342 Proceedings of the British Association, 



pointing out to them those places where the chances are favourable 

 to mining operations, and by inducing them to avoid those bubble 

 speculations at this moment so unfortunately common. — Mr Hop" 

 kins was called upon to make some observations regarding the di- 

 rection of the fissures mentioned by Mr De la Beche, but he did not 

 enter very fully into any discussion, as he proposed, on the follow- 

 ing day, to bring the general consideration of fissures before the 

 Section. He observed, however, that there must have been one 

 great axis of disturbance, to which the smaller fissures must either 

 have been parallel, or have circulated around it ; indeed, Mr De la 

 Beche had supposed the great line of fissures from Blackdown to 

 Cornwall had been curved by the intervening granites. He stated, 

 that there must be a connexion between the width of lodes and 

 their mineral contents ; also, that in the production of fissures there 

 must have been several periods of elevation — Mr Fox then men- 

 tioned a remarkable experiment which he had made upon the yel- 

 low sulphuret of copper, having changed it by electricity into the 

 grey sulphuret. In a trough a mass of clay was placed, so as to 

 divide it into two portions, in one of which was sulphate of copper 

 in solution, in the other dilute sulphuric acid. On the electric 

 communication being made by placing the yellow sulphuret in the 

 solution of sulphate of copper, and a piece of zinc in the acid, the 

 change of sulphuret took place, and crystals of native copper were 

 also formed upon it. — Mr Fox observed, that native copper is not 

 found in the mines of Cornwall combined with yellow copper, but 

 with black copper-ore; and that the grey ore is generally found nearer 

 the surface than the yellow, and also in and near the cross courses. — 

 Mr Taylor bore testimony to the importance of geological informa- 

 tion to mining agents, who now were informing themselves, not 

 only in practice, but in theory. He spoke of the exertions of the 

 late Mr Phillips, in drawing up a geological map of Cornwall, so 

 far back as 1800. He suggested the propriety of tracing the lines 

 of fissures into the coal districts, and also wished the directions of 

 the lead lodes of the mountain limestone to be ascertained, as likely 

 to lead to general results. 



Section D. — Zoology and Botany. 



Dr Richardson resumed the reading of his Report on the Zoology 

 of North America. In touching upon the geographical distribution 

 of the Mammalia, he remarked the great similarity which existed 

 between them and the European species ; whilst there was the 



