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November 18, 1848. 

 Dr. D. H. Storer, Vice-President, in the Chair. 



Present, twenty-four members. 



Mr. J. D. Whitney exhibited and described a large 

 reflecting goniometer, made by August Oerthng, in BerHn. 

 This instrument is in its general form and arrangement sim- 

 ilar to that described by Mitscherlich, in the Transactions 

 of the Berlin Academy ; it has, however, several improve- 

 ments over any other instrument which has been as yet con- 

 structed. The execution of the work is highly creditable 

 to the maker, who is well known as one of the most skilful 

 and ingenious workmen in Germany. 



By a slight change in the arrangement of some of the 

 parts, this instrument may be used for the determination of 

 indices of refraction, and for other purposes in physical 

 research, when nice angular measurements are required. 

 The graduation is on silver, and reads by two verniers 

 to 10^'. 



Mr. Whitney read a paper containing the results of the 

 chemical examination of certain American minerals. The 

 mineral named by Nuttall, Nemalite, and since analyzed by 

 Thomson and Connell, with very discordant results, is simply 

 a fibrous hydrate of magnesia, as was supposed by Nuttall 

 himself without analysis. The name Nemalite ought not 

 to be continued, since the substance differs only from 

 Brucite, or hydrate of magnesia, by being in a fibrous state. 

 Mr. Whitney read a description and analysis of a mineral 

 from the north shore of Lake Superior, which had been 

 hastily and incorrectly examined by Mr. Le Conte, and 

 named by him, Coracite. This mineral contains the oxide of 

 uranium, U, combined with oxide of lead and lime, also, 



