62 URANIUM, ANTIMONY, CHROMIUM, &c. 



SECT. V. 



OF THE ATOMIC WEIGHT OF TUNGSTEN. 



THE only chemist who has hitherto attempted to 

 determine the atomic weight of tungsten and its 

 compounds is Berzelius.* He has shown that 

 this metal combines with two proportions of 

 oxygen, and forms two oxides. The protoxide 

 has a flea brown colour, and, when heated, burns 

 like tinder, and is converted into tungstic acid. 

 The peroxide, or tungstic acid, has a yellow co- 

 lour, when obtained from wolfram by the usual 

 process. When strongly heated, it becomes 

 green ; and, if we prepare it by heating tung- 

 state of ammonia in close vessels, its colour is 

 blue. Berzelius has shown that tungstic acid, of 

 all these three colours, is the same in its compo- 

 sition. He formed protoxide of tungsten by 

 putting tungstic acid into a glass tube, heating 

 it to redness, and passing a current of hydrogen 

 gas through the red hot acid, till it ceased to pro- 

 duce any farther change. 



100 parts of this protoxide, when converted 

 i nto tungstic acid, became 107 parts. From this 

 ex P er i ment f Berzelius it is obvious that tung- 

 its ox .. stic acid is a compound of 



Annals of Philosophy, III. 24-4-. 



