BARIUM. 57 



BARIUM. 



For determining the atomic weight of barium we have a 

 series of six ratios, established by the labors of Berzelius, 

 Turner, Struve, Pelouze, Marignac, and Dumas. Andrews* 

 and Salvetat,t in their papers upon this subject, gave no 

 details nor weighings ; and, therefore, their work may be 

 properly disregarded. First in order in point of import- 

 ance, if not first chronologically, is the ratio between silver 

 and anhydrous barium chloride, as determined by Pelouze, 

 Marignac, and Dumas. 



Pelouze,t in 1845, made the three subjoined estimations 

 of this ratio, using his well known volumetric method. A 

 quantity of pure silver was dissolved in nitric acid, and the 

 amount of barium chloride needed to precipitate it was ac- 

 curately ascertained. In the last column I give the quan- 

 tity of barium chloride proportional to 100 parts of silver : 



3.860 grm. BaClj ppt. 4.002 grm. Ag. 96.452 



5.790 " 6.003 " 96.452 



2.895 " 3-OOI " 96.468 



Mean, 96.4573, zb .0036 



Essentially the same method was adopted by Marignac || 

 in 1848. His experiments were made upon four samples of 

 barium chloride, as follows. A, commercial barium chlo- 

 ride, purified by recrystallization from water. B, the same 

 salt, calcined, redissolved in water, the solution saturated 

 with carbonic acid, filtered, and allowed to crystallize. C, 

 the preceding salt, washed with alcohol, and again recrys- 

 tallized. D, the same, again washed with alcohol. For 100 

 parts of silver the following quantities of chloride were re- 

 quired : 



* Chemical Gazette, October, 1852. 



f Compt. Rend., 17, 318. 



J Compt. Rend., 20, 1047. Jouin. fur Prakt. Chem., 35, 73. 



II Arch. d. Sci. Phys. et Nat., 8, 271. 



