118 THE ATOMIC WEIGHTS. 



BARIUM. 



For the atomic weight of barium we have a series of eight ratios, estab- 

 lished by the labors of Berzelius, Turner, Struve, Marignac, Dumas, and 

 Richards. Andrews* and Salvetat,f in their papers upon this subject, 

 gave no details nor weighings, and therefore their work may be properly 

 disregarded. First in order, we may consider the ratio between silver 

 and barium chloride, as determined by Pelouze, Marignac, Dumas, and 

 Richards. 



Pelouze, J 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 carefully ascertained. In the last column I give the 

 quantity of barium chloride proportional to 100 parts of silver: 



3.860 grin. BaCl 2 ppt. 4.002 grm. Ag. 96.452 



5.790 " 6.003 " 9 6 -452 



2.895 " 3-Qoi " 96.468 



Mean, 96.4573, .0036 



Essentially the same method was adopted by Marignac in 1848. His 

 experiments were made upon four samples of barium chloride, as fol- 

 lows. A, commercial barium chloride, 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 recrystallized, D, the 

 same, again washed with alcohol. For 100 parts of silver the following 

 quantities of chloride were required, as given in the third column : 



Ag. BaCL. Ratio. 



* Chemical Gazette, October, 1852. 



fCompt. Rend., 17, 318. 



I Compt. Rend., 20, 1047. Journ. fur Prakt. Chern., 35, 73. 



g Arch, d. Sci. Phys. etNat., 8, 271. 



