ATOMIC WEIGHTS 193 



Mean, 72.694, ± .0320 



Hence Ba- 137.48. 



Assigning to Berzeliiis' work equal weight with that of Turner, the 

 four series representing the ratio 2AgCl : BaCl, combine as follows: 



Berzelius 72.427, ± .0154 



Turner 72.680, ±: .0154 



Richards 72.653, ± .0014 



Thorpe 72.694, ± .0320 



General mean 72.650, ± .0014 



The ratio between barium nitrate and barium sulphate has been de- 

 termined only by Turner.^ According to his experiments 100 parts of 

 sulphate correspond to the following quantities of nitrate : 



112.060 

 111.990 

 112.035 



Mean, 112.028, ± .014 



Hence Ba= 136. 338, ±.2706. 



For the similar ratio between barium chloride and barium sulphate, 

 there are determinations by Turner, Berzelius, Struve, Marignac and 

 Eichards. 



Turner* found that 100 parts of chloride ignited with sulphuric acid 

 gave 112.19 parts of sulphate. By the common method of precipitation 

 and filtration a lower figure was obtained, because of the slight solubility 

 of the sulphate. This observation bears directly upon many other atomic 

 weight determinations. 



i-Phil. Trans., 1833, 538. 

 - Pliil. Trans., 1829, 291. 



