THE TRUE ATOMIC WEIGHT OF BROAIINE. 

 (Plates XXXIV.-XXXVI.) 



By dr. GUSTAVUS HINRICHS. 

 (Read April 4, 1913.) 



Highly important laboratory work, undertaken for the purpose 

 of determining the atomic weight of bromine, has quite recently 

 been done by Dr. H. C. P. Weber.^ Ten complete syntheses of 

 hydrogen bromide were made, taking from 60 to 80 grammes of 

 bromine for the individual determinations. 



Employing the method of reduction in general use by the domi- 

 nant school, Mr. Weber finds the atomic weight of bromine to be 

 79.924 with the insignificant "probable error" of 0.0014, oxygen 

 at 16 exactly being taken as the standard.- Accordingly, the atomic 

 weight of bromine should fall between 79.923 and 79.925, for 

 = 16. 



Now bromine is one of the ten fundamental elements of the 

 system of Stas (Ag, Pb, Na, Ka ; CI, Br, lo ; N, S, O). If the 

 above value for Br should be found to be in error, such error would 

 affect the values of most of the other nine elements also. 



During the last twenty years, I believe to have demonstrated,^ 

 by close mathematical examination of all the atomic weight determi- 

 nations made during the entire century (since Berzelius began this 

 work in 1810) that the method in common use for the reduction of 



1/;;;/. Am. Chem. Soc, Oct., 1912, pp. 1294-1310. 



~ L. c, pp. 1309-13 10. 



^Special Works: "True Atomic Weights," 1894; "Absolute Atomic 

 Weights." 1901 ; " Proximate Constituents," 1904. Twenty-five Notes in the 

 Comptes Rendxis, in twelve years from 1892 to 1912; (in nine years no note 

 on atomic weights) ; Moniteur Scientifique, thirteen papers from 1906-1909; 

 Revue generate de Chimie, 1910, on hydrogen; Proceedings American Philo- 

 sophical Society, 1910, 1911; Proceedings Am. Assoc. Adv. Science, 1869. 



PROC. AMER. PHIL. .SOC, LII, 211 Q, PRINTED OCT. \ \, 1913. 



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