BROMINE. 21 



gave a residue of 0.973 potassic sulphate. [If this analysis 

 is calculated with Stas' atomic weights, it gives Br = 74.65.] 

 In another experiment 100 parts of argentic bromide reduced 

 with zinc, the excess of which was extracted with sulphuric 

 acid, gave 58.9 parts silver. [Calculated with Stas' data 

 this gives Br = 75.3.] Balard mentions no special precau- 

 tions in the preparation of his salts for this determination. 

 {Annal. de Chimie et de Physique, 32, 1826, 357, 362.) 



J. Liebig: 75.29 (0 = 16); 470.55 (0 = 100). 



2.521 potassic bromide precipitated with argentic nitrate 

 gave 4.041 argentic bromide. The potassic bromide was 

 obtained by adding potassic hydrate to an alcoholic solution 

 of bromine until the solution began to lose color. {Annal. 

 de Chimie et de Physique, 33, 1826, 331.) 



J. J. Berzelius : 78M4. (O = 16) ; 489.15 (0 = 100). 



Berzelius suspected that insufficient precautions had been 

 taken in the preceding determinations to get rid of chlorine. 

 He washed bromine for a long time, and converted it into 

 zinc bromide and ammonium bromide. These salts he par- 

 tially precipitated with argentic nitrate to get rid of chlorine. 

 From the filtrate he precipitated argentic bromide which he 

 washed, dried, and melted. 7.202 of this bromide, decom- 

 posed in a current of chlorine, yielded 5.546 argentic chlo- 

 ride; 7.8805 bromide gave 6.069 chloride. If Ag = 1351.607, 

 and CI = 442.652, the mean value of Br is as above ; differ- 

 ence, 0.09. [Poggend. Annal., 1^^ 1828, 565 ; Kongl. vet. 

 Akad. Handl, 1828.) 



C. Loewig: 75.76 (0 = 16). 



According to Gmelin-Kraut, Handbuch der Chemie, the 

 determination was published in a treatise entitled Brom und 

 Seine Chemische Verhdltnisse, Heidelberg, 1829. 



C. Marignac : 79.957 (0 = 16). 



In three experiments a known weight of silver was dis- 

 solved in nitric acid, precipitated with potassium bromide, 

 and the argentum bromide dried at 200° and weighed. [For 

 Ag = 107.93 these experiments give Br = 79.938, with an 

 extreme difference of 0.018.] In vacuo this result is, accord- 

 ing to Stas, 79.968. In seven experiments a known weight 

 of silver was precipitated by a determinate amount of potas- 

 sic bromide by titration. [If K = 39.137, and Ag = 107.93, 



