341 



The research was afterwards extended so as to embrace speci- 

 mens from a large number of localities, including Hoboken, 

 N. J., Chester, Lynnfield, and Newbury, in Massachusetts, and 

 some European samples of wrought serpentine from ancient 

 cities. These have all afforded anhydrous carbonate of mag- 

 nesia as a constituent part of the composition both chemically 

 and mechanically considered. They also confirm, in a general 

 manner, the evidence that earlier analyses afforded of the com- 

 plex characters of serpentine rock. 



As an illustration of the chemical and mechanical composition 

 of a Verd Antique Marble from Europe, Dr. Hayes exhibited a 

 polished specimen, which having a mottled surface of green and 

 white, agreeably blended, was a beautiful marble. With the 

 specimen, were the two minerals which formed its basic or green 

 component part, as removed by chemical means, and these were 

 scales of talc, and prismatic fragments of clear green asbestos. 

 The composition of this Verd Antique is, in 100 parts. 



Granular Carbonate of Lime - 42.60 



Compact Asbestos and Talc .... 55.00 



Carbonate of Magnesia 1.92 



Moisture 12 



99.64 



The asbestos and talc containing 5.20 combined water, after 

 drying at 212° F. 



Dr. Jackson, in reply to Dr. Hayes, said that his own analyses 

 of the Serpentines of Vermont and of Massachusetts, agree per- 

 fectly with those of European Serpentine, made by himself, and 

 by many of the most celebrated analytical chemists of Europe ; 

 that he could not conceive how the presence of carbonate of 

 magnesia could possibly have been overlooked by so many 

 chemists, or how their analyses could balance so well as they 

 do, if carbonic acid were present in any considerable quantity, as 

 would be the case if the magnesia were in the state of a carbonate 

 and not a hydrous silicate in Serpentine ; for anhydrous carbonate 

 of magnesia contains 51.69 per cent, of carbonic acid. 



Pure crystallized Serpentine contains — 



