14 THE ATOMIC WEIGHTS. 



This value is exactly that which Stas deduced from both 

 of his own series combined, and gives great emphasis to his 

 wonderfully accurate work. It also finely illustrates the 

 compensation of errors which occurs in combining the fig- 

 ures of different experimenters. 



Similar analyses of silver chlorate have been made by 

 Marignac and by Stas. Marignac's figures I have not been 

 able to find,* and Stas gives but two experiments. The fol- 

 lowing are liis percentages of oxygen in silver chlorate :t 



25.081 

 25.078 



Mean, 25.0795, zt .0010 



For the direct ratio between silver and chlorine there are 

 seven available series of experiments. Here, as in many 

 other ratios, the first reliable work was done by Berzelius.J 



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 w^as precipitated 

 and collected on a filter. In the second and third experi- 

 ments the solution was mixed with hydrochloric acid in a 

 flask, evaporated to dryness, and the residue then fused and 

 weighed without transfer. One hundred parts of silver 

 formed of chloride : 



* Since all the calculations were finished I have secured a copy of Marignac's 

 figures. They are as follows : The third column gives the percentage of O in 

 AgClOj. 



24.510 grm. AgClOg gave 18.3616 .-VgCl. 25.103 



25.809 " " 19-3345 " 25.086 



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, dz .0044 

 The introduction of these figures into the subsequent calculations could not 

 produce any appreciable result. They would practically vanish from the general 

 mean. However, they serve here as confirmation of Stas' work. 

 f Aronstein's Translation, p. 214. 

 J Thomson's Annals of Philosophy, 1820, v. 15, ]). 89. 



