158 ABSOLUTE ATOMIC WEIGHT. 



On the True Atomic Weight of Boron.* 



" The substance which must be taken as standard of matter 

 for the fundamental data of Chemistry, the Atomic Weights, 

 is the Diamond ; C = 12, exactly. See : Apergu du Syste"me 

 des Poids Atomiques de precision, fonde* sur le diamant 

 comme matiere e*talon (Comptes Rendus, T. 117, pp. 1074- 

 1078; 1893.) 



"The crystallized carbides produced by Mr. Moissan 

 have suggested to me an entire series of direct determina- 

 tions of precision. See : True Atomic Weights, pp. 175-176, 

 Saint Louis; 1894. 



u Mr. Henry Gautier has recently made the first two deter- 

 minations of this kind, in the Laboratory of Mr. Moissan. 

 Comptes Rendus, T. 129, pp. 595-598; 1899. 



" In the first determination, 268.6 milligrammes of boron 

 "carbide gave him 151.5 mgr. of carbon dioxide; in the 

 " second determination, 326.8 mgr. of carbide gave him 

 ' 184.4 dioxide." 



" In order to avoid the introduction of errors in the 

 " calculation or by the use of auxiliary data which might be 

 " inexact, it is best to proceed according to my General 

 {i Method for the Calculation of Atomic Weights, published 

 " in the Comptes Rendus, T. 116, pp. 695-698; 1893." 



"The common atomic weight of boron being n, the 

 unit of weight of the carbide (Boe C = 78) must give 0.56 410 

 of the dioxide (COa =44). 



"According to the first determination, the 268.6 of 

 carbide ought to have given 151.52 mgrs. of dioxide, which 

 is 0.02 mgrs. more than the value obtained by Mr. Gautier. 



" In the second determination, the 268.6 mgrs. of carbide 

 ought to have given 184.34 mgrs. of dioxide, or 0.06 mgrs. 

 less than the amount found by Mr. Gautier. 



" Since these minute deviations are entirely below the 

 limit of the weighings, it follows from the determinations 

 of Mr. Henry Gautier that the common atomic weight of 



*This is a correct and complete translation of my paper published in 

 the Comptes Rendus, T. 131, pp. 1712-1714; 1900. 



