118 



THE ATOMIC WEIGHTS. 



BARIUM. 



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

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

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

 gave no details nor weighings, and therefore their work may be proper!}'- 

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

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

 Richards. 



Pelouze, X ii^ 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 l^arium chloride proportional to 100 parts of silver: 



I 



3.860 grrn. BaCIj ppt. 4.002 grm. Ag. 

 5.790 " 6.003 



2.895 " 3001 " 



96.452 

 96.452 

 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 crvstallize. 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 : 



( 3.4445 

 ■j 3.7480 

 (.6.3446 

 4.3660 

 4.8390 

 6.9200 

 5.6230 



f 5.8435 



^- 1 4.8225 

 1^6.8460 



A. 



C. 



BaCl.,. 



3.3190 

 3.6110 

 6. 1 140 

 4.1780 

 4.6625 

 6.6680 

 5.4185 

 5.6300 

 8.2650 

 4.6470 

 6.5980 



Ratio. 



96.356 ~^ 



96.345 K Mean, 96.354 



96.362 3 



96.356 



96.352 



96.358 



96.363 



96.346] 



96.384 1 



96.361 j 



96.377 J 



Mean, 96.354 



Mean, 96.360 



Mean, 96.367 



Mean, 96.360, dz .0024 



* Chemical Gazette, October, 1852. 



t Compt. Rend., 17, 318. 



I Compt. Rend., 20, 1047. Journ. fur Prakt. Chem., 35, 7; 



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



