*>1 



oJ 



on the contrary, the Wcs^torn conl-fickl?^, liiglily bituminous and 

 inidislurbed, have probably been formed witliout such agency. 

 From this it would apjjcar that anthracite or bituminous coal 

 may be formed from the same plants, according to the presence 

 or absence of heat, water, and pressure. 



Mr. Stodder observed that a similar theory had been offered, he 

 believed, by Mr. T. S. Hunt ; and also by Prof. Rogers, who 

 ascribed the change to the presence of heated steam. 



Dr. Jackson alluded to the manner in which the native copper 

 and silver of Lake Superior are formed ; in his opinion from the 

 chlorides of these metals in contact with iron, as he had exjjlained 

 at a previous meeting in regard to gold. It is well known that at 

 the junction of the trap with the metalliferous vein, the rock be- 

 comes brown from the oxidation of the iron. When once depos- 

 ited, it continues to be formed by the operation of the same 

 causes ; and when the copjDcr is deposited, pure metallic silver, 

 formed from the chloride, is plated upon it ; the two metals, 

 chemically pure, are in contact, yet unalloyed. The old theory 

 of the formation of these deposits from acid solutions is unsatis- 

 factory, and unable to account for the absence of the ordinary 

 lime salts. 



The resignation of Mr. A. E. Agassiz as Curator of 

 Entomology was announced and accepted ; and Dr. Dur- 

 kee and the Secretary were appointed a committee to 

 nominate his successor. 



Dr. John C. Reinhardt, of Sorocaba, Brazil, was chosen 

 a Corresponding Member of the Society ; and Messrs. 

 William Putnam, of Boston, and Emanuel Samuels, of 

 Mattapan, Resident Members. 



