TRANSACTIONS OF THE SECTIONS. 81 



These joints therefore cannot have determined the directions of disloca- 

 tion, while the local deviations just alluded to, so far as nothing similar 

 to them has yet been observed in the directions of joints, offer a strong 

 proof that the lines of fracture have not been determined by the joints 

 of the inferior portion of the mass, but by the mode of action of the 

 elevatory force. 



Notes on the Sea Rivulets in Cephalonia: By Lord Nugent. 



At the extremity of a rocky promontory, Point Theodori, in the har- 

 bour of Argostoli, streams of water may be observed rushing inland by 

 means of large fissures ; and Lord Nugent stated that Mr. Stephens had 

 excavated pits and channels which he had turned to a profitable purpose 

 by placing a mill in its course. The level of the water appears to be 

 regulated by the height of the tide, and by the fresh waters which oc- 

 casionally flow in. 



On the State of the Chemical Theory of Volcanic Phtenomena. By C. 

 Daubeny, M.D., F.R.S., Professor of Chemistry, Oxon. 

 In this communication Dr. Daubeny reviewed the hypothesis of vol- 

 canic action involving chemical principles, and defended the opinion 

 which ascribes volcanic excitement to the admission of water to the 

 metallic bases of the earths and alkalis in the interior parts of the earth. 



On Voltaic Agencies in Metalliferous Veins. By R. W. Fox. 



R. W. Fox submitted to the Geological Section an experiment tend- 

 ing to show that the native yellow, or bisulphuret of copper, is convert- 

 ible into the grey sulphuret of that metal by voltaic agency. To effect 

 this he employed a trough divided into two cells by a mass or wall of 

 moistened clay. In one of these cells he put a piece of the yellow 

 sulphuret of copper, and a solution of the sulphate of copper ; in 

 the other cell a piece of zinc, attached to the copper ore by means 

 of a copper wire which passed over the clay, and he filled the 

 latter cell with water. This simple voltaic arrangement quickly 

 changed the surface of the copper ore from yellow to beautiful iridescent 

 colours, afterwards to purple copper, and finally, in a few days, to 

 grey copper, on which metallic copper was abundantly deposited in 

 brilliant crystals. He considered that the oxide of copper in the solu- 

 tion parted with its oxygen to one portion of the sulphur of the bisul- 

 phuret of copper, thus forming sulphuric acid, which was transmitted 

 by the voltaic action through the clay to the zinc in the other cell, 

 whilst the deoxidized copper was deposited on the electro-negative cop- 

 per ore. 



These results seemed to explain the reason why metallic copper is 

 often found in contact with grey and black copper ore in our mines, 

 and not with the yellow sulphuret of that metal, and likewise, why the 

 former generally occurs in metallic veins, nearer the surface and cross 

 courses than the yellow sulphuret ; in fact, in situations in which it is 



VOL. V. — 1836. 6 



