OF ARTS AND SCIENCES. 359 



apparent inexactness of certain chemical analyses, as well as facts in 

 mineralogy which at present are not reconcilable with the laws of 

 atomic proportion ; and would show that, where a deviation from these 

 laws is coexistent with crystalline structure, such deviation may be 

 merely apparent, and the crystalline form in reality dependent upon 

 the presence of a body possessed of a definite atomic constitution. 



Dr. C. T. Jackson exhibited a fragment of the Dhurmsala 

 meteorite, which had been presented to the Boston Society of 

 Natural History by the Governor-General of India. 



Mr. Safford announced the results of his calculations on the 

 perturbations of Uranus. 



Five huntlred and second meeting. 



January 14, 1862. — Monthly Meeting. 



The President in the chair. 



The Corresponding Secretary read various letters relative to 

 the exchanges of the Academy. 



F. H. Storer having declined to serve on the Rumford Com- 

 mittee, Prof. Winlock was chosen to fill the vacancy. 



The Report to the United States Government on the 

 Physics and Dynamics of the Mississippi, by Capt. Humphries 

 and Lieut. Abbot, of the U. S. Topographical Engineers, 

 received by the Academy from the authors, was referred to 

 Professor Peirce. 



W. P. Dexter communicated the following paper, viz. : — 



Remarks upon the Recent Determinations of the Atomic Weight 



of Antimony. 



The atomic weight of antimony has been successively investigated 

 by Berzelius, Kessler, Schneider, H. Rose, myself, and Dumas. Very 

 recently Kessler has revised and repeated his determinations, and 

 arrived at a result which " completely agrees " * with that previously 



* " Welches (das Atomgewieht) sich nun nach meinen spateren Versuchen als 

 durchaus ubereinstimmend rait dem von Dexter gefundenen herausstellt." — Pogg. 

 Ann., Bd. CXIII. S. 134. 



