42 atomic weight determinations. 



A.Laurent: 35.5 (0=16); 221.88 (0 = 100). 



A single experiment was made as follows : pure silver 

 was weighed otf and placed in a matrass, nitric and chlor- 

 hydric acids were added, the liquid was evaporated and 

 the chloride melted. An empty test was carried on at the 

 same time to act as tare. Silver was taken at 1350. {Paris 

 Comptes Bendus, 20, 1849, 5.) 



J. Dumas : 35.5 (0 = 16). 



Determined by chloridizing different weights of pure silver 

 by heating the metal in a current of chlorine. Experiments 

 on 10 grammes and 20 grammes gave a mean of 35.5055, 

 the difference being 0.013, for chlorine, if silver is 108. 

 {Annal. de Chimie et de Physique, (3,) 55, 1859, 135.) 



J. S. Stas: 35.457 (0 = 16). 



Stas found the atomic weight of chlorine by three inde- 

 pendent methods : 



(1.) From analysis of argentic chlorate and synthesis of 

 argentic chloride. A known weight of the chlorate was 

 dissolved in water, precipitated with sulphuric acid to secure 

 advantageous division of the salt, and reduced while in 

 suspension by a slow stream of sulphurous anhydride. The 

 chloride was washed, dried, and weighed in the flask in which 

 it was produced. The minute amount of chloride present 

 in the chlorate was collected and taken into consideration, 

 and the wash-water was carefully examined for silver. Two 

 analyses (of about 140 and 260 grammes) gave for the 

 molecular weight of the chloride 143.383 and 143.407, mean 

 143.395. A variety of syntheses of argentic chloride in the 

 wet and in the dr}- way showed that 100 parts silver com- 

 bined with nearl}^ 32.850 parts chlorine. Stas assumes that 

 none of his syntheses can possibly have given too mu(;h 

 chloride and accepts the relation stated. These data give 

 01 = 35.458. 



(2.) From the mutual relations of potassic chlorate and 

 chloride and argentic chloride, combined with the composi- 

 tion of the last. The chlorate was decomposed either by 

 gentle heat or in the wet way with chlorhydric acitl. 100 

 parts of chlorate were found to contain 60.846 parts chlo- 

 ride as the mean of eight experiments ; extreme difference, 

 0.012,'which gives the molecular weight of potassic chloride 

 at 74.59. The relation between potassic and argentic chlo- 

 ride was ascertained by Pelouze's method, (see Marignac's 



