ABSTRACTS 



Authors of scientific papers are requested to see that abstracts, preferably 

 prepared and signed by themselves, are forwarded promptly to the editors. Each 

 of the scientific bureaus in Washington has a representative authorized to for- 

 ward such material to this journal and abstracts of official publications should 

 be transmitted through the representative of the bureau in which they originate. 

 The abstracts should conform in length and general style to those appearing in 

 this issue. 



CHEMISTRY.— The atomic weight of bromine. H. C. P. Weber, 

 Bureau of Standards. Bulletin of the Bureau of Standards, in 

 Press. 



A considerable amount of work has been done in order to determine 

 the atomic weight of bromine, and the oft-repeated comparison of the 

 atomic weights of silver and bromine makes it seem that this ratio is 

 known with considerable accuracy. The value accepted for bromine, 

 however, rests almost entirely upon that of silver, and it is of interest 

 and importance to obtain a ratio between it and some other element. 

 For chlorine a number of determinations of the ratio of hydrogen to chlo- 

 rine in hydrochloric acid have been 'made, both by purely physical and 

 by chemical methods. For bromine similar comparisons have not been 

 made. Since the determination of the ratio chlorine: hydrogen was 

 carried out with reasonable ease, it seemed probable that the method 

 might be advantageously applied for the purpose of determining the 

 ratio between hydrogen and bromine. 



The method which was employed by Noyes and Weber 1 was found 

 to give good results in this case. The initial difficulties to be overcome 

 were somewhat greater, which was rather unexpected. They were 

 largely due to the* physical properties of hydrobromic acid gas and were 

 eliminated after the method had been studied for some time and slight 

 alterations in the method of manipulation had been introduced. 



The results obtained are given in Table I. The column headed 

 "discrepancy" gives the differences between H -+- Br and HBr. The 

 remainder of the table is self-explanatory. 



1 Bulletin, Bureau of Standards, 4: 345. 1908. 



464 



