﻿BECKER BROTHERS, 



No. 6 Murray Street, New York, 



Manufacturers of Balances and Weights of Precision for Chem- 

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

 where accuracy is required. 

 April, 1871.— [tf.] 



MINERALOGY AND GEOLOGY. 



PROFESSORS and COLLECTORS interested in the above Sciences and 

 VISITORS to LONDON are invited to inspect SAMUEL HENSON'S 

 Collection of MINERALS, ROCKS, GEMS and PRECIOUS STONES. 



BLOWPIPE CASES AND APPARATUS. 

 Catalogue on application 



SAMUEL HENSON, 



277 STRAND, LONDON, Opposite Norfolk Street. 

 July, 6t. 



AMERICAN JOURNAL OF SCIENCE. 



Founded by Professor Silliman in 1818. 



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

 Natural History, Astronomy, and Meteorology, and giving the latest discoveries 

 in these departments. 



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



Associate Editors : Professors Asa Gray, J. P. Cooke, Jr., and John Trow- 

 bridge, of Cambridge, H. A. Newton and A. E. Verrill, of Yale, and G. P. 

 Barker, of the University of Pennsylvania, Philadelphia. 



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 

 second series of 50 volumes as a two-monthly in 1870. The monthly series com- 

 menced in 1871. 



Twenty copies of each original communication are, if requested, struck off for 

 the author without charge ; and more at the author's expense, provided the num- 

 ber of copies desired is stated on the manuscript or communicated to the printers 

 of the Journal. 



The title of communications and the names of authors must be fully given. 

 Articles should be sent in two months before the time of issuing the number for 

 which they are intended. Notice is always to be given when communications 

 offered, have been, or are to be, published also in other Journals. 



Subscription price $6; 50 cents a number. A few complete sets on sale of 

 the first and second series. 



Address the Proprietors, 



J. D. and E. S. DANA, New Haven, Conn. 



MINERALS 



Sold, Bought and Exchanged. 



Address L. STADTMULLER, 



New Haven, Conn. 



References : Prof- J. D. Dana and Prof. G. J. Brush. 



