ATOMIC WEIGHTS 255 



BORON". 



In the first edition of this book 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 analj^ses of 

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

 weight determinations they will be omitted from the present recalcula- 

 tion, which includes a number of later researches. 



Berzelius ' based his determination upon three concordant estimations 

 of the percentage of water in borax. Laurent " made use of two similar 

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



47.10 1 



47.10 L Berzelius 



47.10 J 



47.15 ■) 



^rj 2Q > Laurent 



Mean, 47.13, ± .013 



Hence B = 11.019. 



In 1869 Dobrovolslry * published a dissertation, in Russian, on the 

 atomic weight of boron. The original I have not seen, and I am there- 

 fore compelled to use the data as cited by Brauner.* According to 

 Dobrovolsky, borax is completely dehydrated by ignition when small 

 quantities of it are taken. "With large quantities, some water is retained. 

 Two series of experiments are given to illustrate this assertion : 



' Poggend. Annal., S, 1. 1826. 



='Journ. prakt. Chem., 47, 415. 1849. 



' Doctoral Dissertation, Kiev, 1869. 



* In Abegg's Handbuch der anorganischen Chemie, Bd. 3, Abth. 1, p. 6. 



