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Manufacturers of Balances and Weights of Precision for Chem- 

 ists, Assayers, Jewelers, Druggists, and in general for every use 

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 April, 1871.— [tf.] 



MINERALOGY AND GEOLOGY. 



PROFESSORS and COLLECTORS interested in the above Sciences and 

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 July, 6t. 



AMERICAN JOURNAL OF SCIENCE. 



Founded by Professor Silliman in 1818. 



Devoted to Chemistry, Physics, Geology, Physical Geography, Mineralogy, 

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Editors: James D. Dana aud Edward S. Dana. 



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Two volumes of 480 pages each, published annually in MONTHLY NUMBERS. 



This Journal ended its first series of 50 volumes as a quarterly in 1845, and its 

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MUSPRATT'S CHEMISTRY. 



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