THE MOLECULAR WEIGHT OF ARGENTIC SULPHATE AND THE 

 ATOMIC WEIGHT OF SULPHUR. 



INTRODUCTION. 



The atomic weight of sulphur has been investigated by many experi- 

 menters; but, as will be seen, the results are far from concordant. A 

 brief review of these investigations forms the most appropriate introduc- 

 tion to the present one. The values in the following list have been recal- 

 culated with modern figures for the other atomic weights involved: 1 



1814. Berzelius (Phil. Trans., 104, 20) ............ 32.0 



1826. Berzelius (Pogg. Ann., 8, 15) ................ 32.08 



1833. Turner (Phil. Trans., 123, 539) ............ 32.00 



Do ........................ 32.06 



1836. Thomson (J. prak. Chem., 8, 370) ........... 32. 



1844. Erdmann and Marchand (J. prak. Chem. 31, 396) . . . 31.99 



1845. Berzelius (Lehrbuch, 5th ed., 3, 1187) ......... 32.04 



Do ........................ 32.16 



1848. Svanberg and Struve (J. prak. Chem., 44, 320) .... 32.15 



1851. Struve (Liebig. Ann., 80, 203) ............ 31.94 



1859. Dumas (Ann. Chim. et Phys. [3], 55, 148) ....... 32.00 



1860. Stas 2 (Bull. Acad. Belg. [2], 10, 153, 322) ........ 32.06 



1878. Cooke (Proc. Amer. Acad., 13, 50) .......... 32.137 



Do ........................ 31.980 



1891. Richards (Proc. Amer. Acad., 26, 268) ......... 32.043 



1898. Leduc (Ann. Chim. et Phys. [7], 15, 94) ........ 32.056 



1899. D. Berthelot (Jour, de Phys. [3], 8, 271) ........ 32.050 



1904. Jaquerod and Pintza (C. R., 139, 129) ......... 32.01 



1905. Guye (C. R., 140, 1242) ............... 32.065 



1905. Jaquerod and Scheuer (C. R., 140, 1384) ........ 32.036 



The work of the predecessors of Stas is now of historical interest only 

 and does not merit detailed criticism ; in recent times the atomic weight 

 of sulphur has rested chiefly upon the experiments of the famous Belgian. 



Stas converted silver into its sulphide by heating it in a current of sul- 

 phur vapor or hydric sulphide; but because he did not know the precau- 

 tions necessary for preparing perfectly pure silver, 3 it is evident that all 

 of his work in which silver was weighed needs revision. Stas also reduced 

 argentic sulphate to silver in a current of hydrogen, but in this case he 



= 107.93; Cl = 35.473; Pb = 206.9 ; Hg = 200.0; Na = 23.008; C = 12.002. 

 ^ 2 Van der Plaats, Ann. Chim. et Phys. [6], 7, 504 and 526 (1886), pointed out that 

 Stas made an error in calculating his own data. Stas obtained 32.074, but 32.06 is 

 correct. 



3 Dumas, Ann. Chim. et Phys. [5], 14, 289 (1878) ; Richards and Wells, Publica- 

 tion Carnegie Inst. No. 28, p. 66 (1905). 



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