258 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54 



General mean of botti, 57.933, ± .0074 



Hence B = 10.957. 



As a check upon the last series of results, the sodium chloride was 

 dissolved in water, and precipitated with silver nitrate. The silver 

 chloride was collected and weighed in a Gooch crucible, and its weight 

 gives a new ratio with anhydrous borax. The cross ratio between the 

 two chlorides, silver and sodium, has already been used in the discussion 

 upon sodium. The new ratio I give in terms of NaoB^O^ equivalent to 

 100 parts of AgCl. 



Mean, 70.546, ± .0146 



Hence B = 11.054. 



Rimbach ^ based his determination of the atomic weight of boron upon 

 the fact that boric acid is neutral to methyl orange, and that therefore 

 it is possible to titrate a solution of borax directly with hydrochloric 

 acid. His borax was prepared from carefully purified boric acid and 

 sodium carbonate, and his hydrochloric acid was standardized by a series 

 of precipitations and weighings as silver chloride. It contained 1.84983 

 per cent, of actual HCl. The borax, dissolved in water, was titrated by 

 means of a weight-burette. I give the weights found in the first and 

 second columns of the following table, and in the third column, calcu- 

 lated by myself, the HCl proportional to 100 parts of crystallized borax. 

 Rimbach himself computes the percentage of Na^O and thence the atomic 

 weight of boron, but the ratio Na.B^O^.lOHoO : 3HC1 is the ratio actually 

 determined. 



1 Ber. Deutsch. chem. Ges., 26, 164. 1893. 



