150 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 54 



1.4055 grm. RbCl gave 1.GGG5 grm. AgCl. 84.338 



1.8096 " 2.1461 " 84.320 



2.2473 •' 2.665 " 84.326 



2.273 " 2.6946 " 84.354 



Mean, 84.3345, ± .0051 



Hence Eb = 85.436. 



Heyeock ' worked by two methods, but unfortunately his results are 



given only in abstract, Avithout details. First, silver solution was added 



in slight deficiency to a solution of rubidium chloride, and the excess 



of the latter was measured by titration. Tlie mean of seven experiments 



gave— 



Ag:RbCl:: 107.93: 120.801 



Hence Eb = 85.287. 



Two similar experiments with the bromide gave — 



Ag:RbBr::107.93:165.437 

 Ag:RbBr::107.93:165.342 



Mean, 165.3895, ± .0320 



Hence Eb = 85.393. 



The determinations by Archibald ' were made with scrupulously puri- 

 fied materials, and with all of the precautions observed in the best modern 

 investigations. The chloride and bromide were precipitated with known 

 weights of silver, and the silver halide produced was also weighed. Two 

 ratios were thus measured for each salt, and checked by the cross ratios 

 between silver and chlorine or bromine, respectively. The weights, cor- 

 rected to a vacuum, are given below, and also the four principal ratios: 



1 Britisl} Association Report, 1882, 449. 

 = Journ. Chcm. See, 85, 776. 1904. 



