64 THE ATOMIC WEIGHTS. 



Now, to combine all five sets of results : 



Penny 157.4417, d= .0033 



Marignac 157.4236, ± .0061 



Stas, 1st series 1 57.4740, zb .0014 



Stas, 2d " 157.4860, it .0003 



Hardin 157-484, ±.0020 



General mean 157-479, ± .0003 



For the direct ratio between silver nitrate and silver chloride there are 

 two series of estimations. A weighed quantity of nitrate is easily con- 

 verted into chloride, and the weight of the latter ascertained. In two 

 experiments Turner* found of chloride from 100 parts of nitrate: 



84357 

 84.389 



Mean, 84.373, -Jz-Oii 



Penny ,t in five determinations, found the following percentages: 



84-370 

 84.388 

 84.377 

 84.367 

 84-370 



Mean, 84.3744, rh .0025 

 The general mean from both series is 84.3743, ± .0025. 



The ratio directly connecting silver nitrate with ammonium chloride 

 has been determined only by Stas. X The usual method of working was 

 followed, namely, nearly equivalent quantities of the two salts were 

 weighed out, the solutions mixed, and the slight excess of one estimated 

 by titration. In four experiments 100 parts of silver nitrate were found 

 equivalent to chloride of ammonium, as follows: 



31.489 

 31-490 

 31.487 

 31.4S6 



Mean, 31.488, rb .0006 



The similar ratio between potassium chloride and silver nitrate has 

 been determined by both Marignac and Stas. 



*Phil. Trans., 1833, 537. 

 tPhil. Trans., 1839. 

 IfAronstein's translation, p. 309. 



