

34 Organic Acids in the Examination of Minerals. 



found at Keyport, N. J., in a clay very rich in carbonaceous 

 matters, are eroded. AH the sharp angles on these pebbles 

 have been rounded, and the surfaces are more or less deeply 

 pitted, as if by some solvent. He has also observed other 

 phenomena of similar character, which he conjectures should 

 be ascribed to the action of organic acids. 



These references would be incomplete without mention of 

 the generalizations of Prof. Henry Wurtz, whose " Scheme of 

 the Geogonic Migrations of Silica throughout the Kingdoms 

 of Life,"* shows thoughtful study and novel views. 



Taken as a whole, the information respecting the part 

 played by organic acids in the changes taking place on the 

 earth's surface, is but small : are we not justified in the belief 

 that some of the reactions disclosed by our researches may in 

 the hands of chemical geologists furnish material for general- 

 izations of no small value 1 ? 



Finally, we are conscious of having treated but a very 

 small number of minerals, compared with those which remain 

 to be studied ; our aim has been to place the methods of 

 examination on record, rather than to exhaust the resources 

 of mineralogy. 



We take pleasure in acknowledging the services of Mr. 

 Edward W. Martin, a student in the Chemical Course at the 

 School of Mines, who has kindly assisted us in a portion of 

 these researches. 



School of Mines, Columbia College, 

 New Yorlc. 



* American Chemist, I, 206. 



