38 THE ATOMIC WEIGHTS. 



work. It also finely illustrates the compensation of errors which occurs 

 in combining the figures of different experniienters. 



Similar analyses of silver chlorate have been made by Marignac and 

 by Stas. Marignac's data are as follows : * The third column gives the 

 percentage of in AgClOg : 



24.510 gim. AgCIOj gave 18.3616 AgCl. 25 103 



25.809 " I9'3345 " 25.0S6 



30.306 " 22.7072 " 25.074 



28.358 " 21.2453 " 25.082 



28.287 " 21.1833 " 25.113 



57.170 " 42.8366 " 25.072 



Mean, 25.088, ±z .0044 



Stas t found the following percentages in two experiments only : 



25 081 

 25.07S 



Mean, 25.0795, dz .oo[o 



Combined with Marignac's mean this gives a general mean of 25,080, 

 dr .0010 ; that is, Marignac's series practically vanishes. 



Tor the direct ratio between silver and chlorine there are seven avail- 

 able series of experiments. Here, as in many other ratios, the first reliable 

 work was done by Berzelius. X 



He made three estimations, using each time twenty grammes of pure 

 silver. This was dissolved in nitric acid. In the first experiment the 

 silver chloride was precipitated and collected on a filter. In the second 

 and third experiments the solution was mixed with h3'drochloric acid 

 in a flask, evaporated to dryness, and the residue then fused and weighed 

 without transfer. One hundred parts of silver formed of chloride : 



132.700 

 132.780 

 132.790 



Mean, 132.757,^.019 



Tui'ner's work § closely resembles that of Berzelius. Silver was dis- 

 solved in nitric acid and precipitated as chloride. In experiments one, 

 two, and three the mixture was evaporated and the residue fused. In 

 experiment four the chloride was collected on a filter. A fifth exj^eri-' 

 ment was made, but has been rejected as worthless. 



The results were as follows : In a third column I put the quantity of 

 AgCl proportional to 100 parts of Ag. 



* Bibl. Univ. de Geneve, 46, 356. 1843. 



t Aronstein's translation, p. 214. 



t Thomson's Annals of Philosophy, 1820, v. 15,89. 



§ Phil. Transactions, 1829, 291. 



