82 ATOMIC WEIGHT DETERMINATIONS. 



FouRCROY AND Thenard, Davy, Wollaston : W0.8 

 (0 = 16); 1255 (0 = 100). 



Fourcroy and Thenard found 8 = 100 Hg. Davy found 

 30 = 880 Hg, giving Ilg = 1266. The latter also found 

 134 CI = 380 Hg, which for CI = 441, gives Hg=1254. 

 {Phil Trans., IO4,, 1814, 21.) 



N. G. Sefstroem : 202.53 (0 = 16); 1265.822 (0 = 



100). 



Determined by three analyses of the oxide according to 

 which 100 Hg = 7.89, 7.9, and 7.97 0. {Berzelius' Lehr- 

 buch, S, 1215.) 



E. Turner : W0.72 (0 = 16). 



Turner made a number of determinations of this atomic 

 weight but regarded the value he adopted, 202, only as 

 an approximation. From the oxide, prepared from nitrate, 

 he got 200.77 and 199.97. The compound was decomposed 

 by heat, and the products carried over silver and gold in a 

 narrow tube. Four experiments were made on mercuric 

 chloride which was decomposed by pure calcic oxide, and 

 the CI precipitated with argentic nitrate. [These analyses 

 recalculated for the Stas' atomic weights of Ag and CI 

 give 202.079, 201.701, 201.815.] Turner also made two 

 experiments on the reduction of the chloride with stan- 

 nous chloride, the Hg being collected, dried and weighed. 

 [These experiments recalculated give 199.423 and 199.289.] 

 The mercuric chloride was purified by recrystallization. 

 Weighings reduced to vacuum. [Phil. Trans., 123, 1833, 

 535.) 



Erdmann and Marchand: 2OO.II1, (0 = 16); 1250.6 

 (O = 100). 



Determined from the mean of four experiments on the 

 reduction of the oxide in a current of carbon di-oxide. 

 Copper, carbon (from sugar) oxide, and carbon, were intro- 

 duced in successive layers in a combustion tube. Dry car- 

 bon di-oxide was passed through and the mercuric oxide 

 heated. The metal was collected in a receiver to which a 

 tube filled with gold foil was appended. The metal was 

 perfectly clean. Moisture was removed by a stream of dry 

 air after distillation. The oxide was purified by heating it 

 to incipient decomposition the metallic fumes being removed 



