BORON. 171 



BORON. 



In the former edition of this work the data relative to boron were few 

 and unimportant. There was a little work on record by Berzelius and 

 by Laurent, and this was eked out by a discussion of Deville's analyses 

 of boron chloride and bromide. As the latter were not intended for 

 atomic weight determinations they will be omitted from the present re- 

 calculation, which includes the later researches of Hoskyns-Abrahall, 

 Ramsay and Aston, and Rimbach. 



Berzelius* based his determination upon three concordant estima- 

 tions of the percentage of water in borax. Laurent f made use of two 

 similar estimations, and all five may be properly put in one series, thus : 



47-10] 



47.10 j- Berzelius. 

 47-ioj 



47- '5 I Laurent. 



47-20* 



Mean, 47.13, .013 



In 1892 the posthumous notes of the late Hoskyns-Abrahall were 

 edited and published by Ewan and Hartog. J This chemist especially 

 studied the ratio between boron bromide and silver, and also redeter- 

 mined the percentage of water in crystallized borax. The latter work, 

 which was purely preliminary, although carried out with great care, gave 

 the following results, reduced to vacuum standards : 



Na^BtPv Per cent. 



7.00667 3.69587 47.2069 



12.95936 6.82560 47.3308 



4.65812 2.45248 47.35 4 



4.47208 3-9395 6 47. 2 7 6 3 



4.94504 2.60759 47.2686 



Mean, 47.2866, db .0171 



Two sets of determinations were made with the bromide, which was 

 prepared from boron and bromine directly, freed from excess of the 

 latter by standing over mercury, and finally collected, after distillation, 

 in small, weighed, glass bulbs. It was titrated with a solution of silver 

 after all the usual precautions. The first series of experiments was as 

 follows, with BBr 3 proportional to 100 parts of silver stated as the ratio : 



*Poggend. Annalen, 8, i. 1826. 



t Journ. fur Prakt. Chem., 47, 415. 1849. 



I Journ. Chem. Soc., 61, 650. August, 1892. 



