TUNGSTEN. 125 



siou into nitride, &c. It was purified by rectification over 

 mercury and potassium. (Liebig's Ann., 7^, 213 ; Laurent 

 mid Gerhardt, Comptes Rend., 1849, 325.) 



TUNGSTEN. 



Regnault has determined the specific heat of tungsten, 

 and Roscoe the vapor density of the chloride. These ex- 

 periments place the atomic weight of tungsten at about 184. 

 {Gmelin-Kraut, I. c; L. Meyer, I. c.) 



J. J. Berzelius : 189M (O = 16) ; 1183.355 (O = 

 100). 



A weighed quantity of tungstic acid was reduced in a 

 current of hydrogen, again weighed, then re-oxidized and 

 reweighed. The number is the mean result of the two 

 operations. The number is given in Berzelius' Lehrbuch 

 as 1188.36 with the data, which are also given in Poggend. 

 Ann., 8, 23. It is pointed out in Graham-Olto that this 

 value must be misprinted, an observation which I have 

 verified. {Poggend. Ann., 4, 1825, 152.) 



Berzelius made an earlier determination than the fore- 

 going by the oxidation of the sulphide, getting 1207. He 

 points out the source of error in this experiment arising 

 from the formation of irreducible sulphate. {Berzelius' 

 Jahresbericht, 5, 1825, 121.) 



R. Schneider : 184.12 (O = 16) ; 1150.78 (O =100). 



Schneider made five experiments on the reduction of 

 tungstic acid with hydrogen in a porcelain tube heated by 

 a charcoal fire. These analyses gave the mean contents of 

 the acid at 79.316 tungsten per hundred ; extreme difier- 

 ence, 0.096. This composition corresponds to an atomic 

 weight of 1150.39. He also made three experiments on 

 the combustion of tungsten, getting a mean of 79.327 

 tungsten per 100 acid ; extreme difference, 0.005, or an 

 atomic weight of 1151.17. The value taken is the mean. 

 The tungstic acid was prepared by decomposing ammonio- 

 tungstic sulphide with chlorhydric acid, washing the pre- 

 cipitate with acid, solution in ammonia, reprecipitation with 

 chlorhydric acid, and so on until a perfectly pure product 

 was obtained. The tungstic acid was finally dried and 



