112 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 54 



Mean, 54.1854, ± .00025 



The five series of determinations combine thus : 



Pelouze 54.141, ± .0063 



Dumas 54.172, ± .0096 



Stas, earlier 54.2078, ± .0002 



Stas, later 54.2047, ± .00045 



Richards and Wells 54.1854, ± .00025 



General mean 54.1995, ± .00015 



In this combination the work of Pelouze and Dumas counts for almost 

 nothing. Stas' determinations carry high weight, and it is not eas}- to 

 understand how their supposed systematic errors could have been so 

 uniform in magnitude. Such errors should vary from experiment to 

 experiment, and so tend to increase the " probable error " of the mean. 



In their research upon the atomic weight of boron, Eamsay and Aston ' 

 converted borax into sodium chloride. In the latter the chlorine was 

 afterwards estimated gravimetrically by weighing as silver chloride on a 

 Gooch filter. Hence the ratio, AgCl : NaCl : : 100 : x, as follows : 



The same ratio was also measured, much more exactly, by Richards 

 and Wells. The occlusion of sodium salts by the silver chloride was 

 especially considered and guarded against. The figure'? obtained are as 

 follows : 



1 Chem. News, 66, 92. 1892. 



