40 ATOMIC WEIGHT DETERMINATIONS. 



tallized sea-salt and concentrated sulphuric acid and was 

 dried by passing through nine tubes filled with sulphuric 

 acid and pummice stone and with calcium chloride. The 

 water was collected in a condenser to which drying tubes 

 were appended. {Paris Comptes Hendus, I4., 1842, 570.) 



A. Laurent : 35.468 (0 = 16) ; 221.672 (0 = 100), 



Determined by three analyses of chloronaphthalintetrach- 

 loride, which he found to contain 58.22 ; 58.29; 58.28 ; per 

 cent. CI. The mean is 58.27 from which the value follows. 

 {Paris Comjjtes Rendus, i^, 1842, 456.) , 



According to Maumene, Laurent confessed that his salt 

 was impure, containing chlorose compounds, in Gerhardt's 

 Comptes Pendus, 1845, "1O8. {Annal de Chimie et de Phusigue. 

 (3,) 18, 1846, 45.) 



C. Marignac: 35.37 (0=16); 221.07 (0 = 100). 



One synthesis of argentic chloride showed that 100 silver 

 equals 32.74 chlorine. Berzelius had found 32.75, which 

 Marignac adopts. Marignac found by six experiments 011 

 the decomposition of potassic chlorate by heat, that the 

 molecular weight of potassic chloride was 932.14. He tested 

 the equivalence of potassic and argentic chlorides by pre- 

 cipitating the former with argentic nitrate, filtering with- 

 out the use of paper through a funnel with a capillary neck. 

 The precipitate was dried and weighed, then melted and 

 reweighed, no loss being observable. 100 potassium chlo- 

 ride gave 192.33 and 192.34 argentic chloride in two ex- 

 periments, or reduced to vacuum, 192.26. Hence the atomic 

 weight is 442.13. The potassic chloride was prepared by 

 heating chlorate which had been purified by repeated 

 recrystallizations. {Liebifs Annal, ^, 1842, 23.) 



C. Marignac: 35.4S6 (0 = 16); 221.6 (0 = 100). 



Li accordance with Pelouze's suggestion, Marignac re- 

 peated his determination of the composition of argentic 

 chloride and of the equivalence of potassic and argentic 

 chlorides, retaining the molecular weight of potassic chlo- 

 ride mentioned in the last paragraph. That value was 

 obtained from the mean of six experiments on the decom- 

 position of the chlorate which gave the percentage of oxygen 

 at from 39.155 to 39.167 ; mean 39.161. Pelouze had got, as 

 the mean of three experiments, 39.157. {Paris Comptes Pendus, 

 15, 1842, 959.) Marignac made eleven experiments on the 

 equivalence of silver and potassium chloride by Pelouze's 



