PROCEEDINGS 



AMERICAN ACADEMY 



ARTS AND SCIENCES. 



VOL. XIII. 

 PAPERS READ BEFORE THE ACADEMY, 



I. 



REVISION OF THE ATOMIC WEIGHT OF ANTIMONY. 

 By Josiah p. Cooke, Jr., 



Erving Professor of Chemisti-y and Mineralogy in Harvard College. 



The first determination of what we now call the atomic weight of 

 antimony was made by Berzelius, and the result published in 1818.* 

 His method consisted in oxidizing the metal with nitric acid and 

 igniting the residue. This product he called antimonious acid ; and, 

 after a careful study of the chemical relations of the several oxides and 

 of the native sulphide of antimony, he assigned to antimonious acid the 

 symbol Sb O^, that of the basic oxide being Sb Og, and of the native 

 sulphide Sb Sg. In some earlier experiments,! Berzelius had not 

 obtained constant results with the same process^, 100 parts of " pure 

 antimony" having yielded in four experiments 125.8, 126, 127.5, and 

 127.8 parts of antimonious acid respectively; but in his later paper he 

 attributes the discordance to the circumstance that he had previously 

 conducted the process in glass flasks, " which could not bear a suffi- 

 ciently strong heat to change all the yellow residue into white oxide." 

 By the later experiments, in which platinum vessels were used, he 

 found that 100 parts of antimony yield 124.8 parts of antimonious acid. 

 But although he distinctly states " that when pure antimony is oxidized 



* Schweigger Jour, fiir Chera. und Phys., xxii. 70, 1818. 

 t Ibid., vi. 149, 1812. 



VOL. XIII. (n. S. v.) 1 



