BORON AND FLUORINE. 63 



drous) for the decahydrate and by using dilute sulphuric acid 

 instead of hydrochloric acid in the titration. His determinations, 

 which were probably largely preliminary in character, have been 

 published only in abstract. The experimental data on the titra- 

 tion of borax privately communicated to Brauner 1G upon the 

 latter's request are not sufficient for a complete recalculation. 

 In the abstract read before the Chemical Society it is stated : 



"A given weight of fused borax was dissolved in water and titrated 

 with dilute sulphuric acid, the strength of which had been determined 

 (I) by titration with solution of pure soda of known strength, (II) as 

 barium sulphate. The value 10.928 was obtained for the atomic weight 

 of boron as a mean of two experiments performed by this method." 17 



The quantities of S0 4 , given by Brauner, equivalent to the 

 portions of borax used are probably the values calculated by Armi- 

 tage himself. The experimental data upon which these calcula- 

 tions were based (weight of BaSO 4 , etc.) have not been published. 



SUMMARY. 



The results and conclusions arrived at in the preceding investi- 

 gation may be summarized as follows: 



(1) Anhydrous sodium tetraborate, by treatment with appro- 

 priate acids and by repeated evaporation with methyl 

 alcohol, was converted, both directly and indirectly, into 

 the chloride, fluoride, sulphate, nitrate, and carbonate of 

 sodium. 



(2) The borax used for this purpose was prepared by synthesis 

 from pure sodium carbonate and boric acid. The latter 

 had been obtained by the saponification of distilled methyl 

 borate. 



(3) The complete dehydration of borax was found to be quite 



difficult and could be effected only by prolonged fusion. 

 "Borax glass," as obtained ordinarily, was found to hold 

 about 0.2 per cent, of water. The complete removal of 

 the latter, without loss of borax by volatilization, was 

 probably effected for the first time and, of course, was of 

 the utmost importance in an investigation of this kind. 

 The difficulty encountered in the complete dehydration 



18 Op. cit., p. 9. " Chem. N. 77, 78 (1898). 



