386 Geological Society. 



gas at its surface, whilst, in consequence of its being attacked 

 and ultimately dissolved by acids, it causes the platina plate 

 covered by it to assume a positive state, and act as such upon 

 a delicate galvanometer. That the substance deposited is 

 not an alkali, or anything very soluble in v^^ater or acids, has 

 been, I think, quite proved ; perhaps it may differ according 

 to the nature of the electrolyte employed. 

 22, Wilmington Square, Sept. 29, 1838. 



LI. Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 

 [Continued from p. 310.] 



June 6th. — A paper was first read, " On Spirolinites in Chalk 

 and Chalk-flints ; " by the Marquis of Northampton, F.G.S. 



The fossils described in this memoir were chiefly found in the 

 flints of Sussex ; and though above two hundred specimens, more 

 or less perfect, have been discovered by the author in that county, 

 he has very rarely met with the genus elsewhere. They have been 

 also found in the same county by the Rev. G. Smith and Mr. Wal- 

 ter Mantell. They occur more frequently in the grey than the black 

 flints ; and are sometimes accompanied by innumerable minute frag- 

 ments of other organic bodies. The size of the best-preserved spe- 

 cimens, including the prolongation, is about one-third of an inch ; 

 and the number of chambers or divisions varies in the same species. 



Of the six species described in the paper, one had been previously 

 named, by Mr. Mantell, Spirolinites Comptoni, and the other five have 

 been named by the Marquis of Northampton, S. Murchisoni, S. Stokesii, 

 S. Lyellii, S. Mantellii, and S. Bucklandii; the author, however, 

 stated that it is exceedingly difiicult to determine satisfactorily 

 specific differences, especially in such minute fossils, imbedded in 

 flint, and exposed only by accidental fracture. 



A communication was next read, entitled, " A Note to accompany 

 Specimens of Quicksilver Ore from the mine San Onofre, near the 

 town of El Doctor, Mexico." By John Taylor, Esq., Treas. G.S. 



Though quicksilver had been known for some time to exist in 

 Mexico, yet few attempts had been made to ascertain to what ex- 

 tent, till the increased prices and demand induced the directors of 

 the Real del Monte and Bolaiios Mining Companies to have re- 

 searches made. Ores of that metal have, in consequence, been dis- 

 covered and traced in districts very remote from each other ; but 

 Mr. Taylor confined his remarks to the locality at which the speci- 

 mens presented to the Society were obtained. 



The ores of San Onofre are chiefly cinnabar, partly hepatic, but 

 native quicksilver occurs, and native calomel. They are stated to 

 exist in a regular vein, two or three yards in width, the gangue 

 consisting of carbonate of hme, with sulphate of barytes, and a small 

 portion of silex. It traverses a limestone hill of considerable height, 

 and appears to have been worked in former times. 



