iy INTRODUCTION. 



found for boron was used in deriving the atomic weight of this 

 element, although some calculations were referred directly to 

 sodium sulphate, and one was based on a cross-ratio between 

 sodium fluoride and sodium chloride. All methods, rather con- 

 sistently, gave the average value 19.005 for fluorine. 



Chapter III consists of a constructive, critical discussion of 

 previous determinations based upon the analysis of borax. 



