126 ATOMIC WEIGHT DETERMINATIONS. 



heated to redness. {Erdmann' s Journ. far Prak. Chem., 50 ^ 

 1850, 163.) 



R. F. Marchanb : ISJ^.l (O = 16) ; 1150.6 (0 = 100). 



Determined from two experiments on the reduction of 

 tungstic acid in a current of hydrogen, and two experiments 

 on the combustion of tungsten. These determinations 

 were made in the same manner as and at the same time 

 with Schneider's. The extreme difference was 3.5 for O = 

 100. (iiV6?^'5^ww., 77, 1851, 263.) 



J. B. VON Borck: 183.816 (O = 16); 1148.85 (0 = 

 100). 



Determined by seven experiments on. the reduction of 

 tungstic acid at a white heat by hydrogen, and by two ex- 

 periments on the combustion of tungsten. The number is 

 the mean; extreme difference, 10.38 for = 100. The 

 tungstic acid was prepared from Wolframite by fusing the 

 mineral with potassium carbonate, solution in water con- 

 taining alcohol, precipitation with calcic chloride and de- 

 composition of the calcic tungstate with chlorhydric acid. 

 The tungstic acid so produced was converted into ammonium 

 salt which, on decomposition, yields a compound free from 

 iron and manganese. {ErdmanrCs Journ. fiir Prak. Chem., 

 54, 1851, 254.) 



A. KiCHE : 174 (0 = 16). 



This value was reached by five determinations of the 

 amount of water produced by the reduction of tungstic 

 acid in a current of hydrogen, which gave a mean of 87.07 ; 

 extreme difference, 1.78. The tungstic acid w^as obtained 

 by heating the ammonium salt, or by the decomposition of 

 the oxychloride produced by heating tungstic acid and 

 carbon in a current of chlorine. {Annul, ae Chini. et de 

 Phys., (3,) 50, 1857, 10.) 



J. Dumas : I84. (0 = 16). 



Dumas made six experiments on the reduction of tungstic 

 acid in hydrogen at a high temperature in a nacelle of un- 

 glazed porcelain, and two experiments on the titration of 

 the chloride with argentic nitrate. The extreme difference 

 between the results was 0.69 for = 8. The acid was pre- 



