20 ATOMIC WEIGHT DETERMINATIONS. 



weights, and gets the value given. {Poggend. AnnaL, S, 1826, 

 19.) 



-A. Laurent: 10.86 (0 = 16). 



Laurent found that borax retains some water even when 

 melted, which, however, can be expelled by the addition of 

 Iceland spar. By repeating Berzelius' experiments, and 

 adding a known weight of spar, he found the water con- 

 tents in two experiments 47.15 and 47.20. He did not 

 regard the experiments as accurate. Gmelin-Kraut recalcu- 

 lates these data with Stas' atomic weights, and gets B = 

 10.91 and 10.81. {Paris Comptes Rendus, 29, 1849, 5.) 



WoEHLER and Deville : 10.87 (0 = 16). 



These chemists titrated the bromide and the chloride of 

 boron with argentic nitrate. They do not offer the analy- 

 ses as atomic weight determinations, but Dumas applies the 

 data to this object. Taking Ag = 108, and CI = 35.5, Dumas 

 calculates from the analysis of the chloride prepared by the 

 action of H CI on B, B := 11 ; from the analysis of the 

 chloride prepared by the action of CI on B, B = 10.6 ; from 

 the analysis of the bromide prepared by the action of bro- 

 mine on boron, B = 11. {AnnaL de Chimie el de Physique, 

 (3,) 53, 1858, 88; 55, 1859, 129.) 



T. Thomson : 10.67 (0 = 16). 



Thomson supposed boracic acid to be composed of one 

 atom of boron and two of oxygen, and concluded from 

 Davy's and his own experiments that the atom of B was 

 exactly equal to that of 0. For the correct composition of 

 the acid his value must be reduced one-third. {System of 

 Chem., 7th ed., 1, 1831, 214.) 



BROMINE. 



!Mitscherlich determined the vapor density' of bromine, 

 and Regnault the specific heal in a solid condition at very 

 low temperatures. Both of these constants correspond to 

 an atomic weight of 80. {Gmelin-Kraut, I. c; L. 31eyer, L c.) 



A. J. Balard : 75 (O = 16) ; 468.85 (0 = 100). 

 1.27 potassium bromide decomposed with sulphuric acid 



