268 F. Wiihler on Tutigsten. 



The chloride of tungsten being decomposed in water Into 

 tungstic acid and hydrochloric acid, must correspond in its 

 composition with the tungstic acid ; — viz, it must be composed 

 of 3 atoms of chlorine, and 1 of tungsten, thus : 



Atoms. 

 Chlorine , . . . 3 ... 35-9 

 Tungsten ... 1 ... 64^'! 

 100-0 

 By an approximative experiment, 0"166 grain of this chlo- 

 ride, dissolved in ammonia, evaporated and heated, yielded 

 0-13 grain of tungstic acid = 62'65 parts of tungsten for 100 

 parts of the chloride. 



Protochloride of Tung&ten. 



This compound is always formed, with a very slight mix- 

 ture of the others, on heating metallic tungsten in chlorine. 

 The metal ignites and is completely converted into chloride, 

 which is presented sometimes under the form of an aggregation 

 of fine tender needles of a deep red, resembling wool, but 

 more frequently as a compact melted mass of a deep red co- 

 lour, with a shining fracture nearly like that of cinnabar. 

 It easily melts, and boils before it is volatilized. Its vapour 

 has a red colour, deeper than that of nitrous acid. In water this 

 chloride soon becomes violet, decomposing gradually and com- 

 pletely into oxide of a violet colour, and hydrochloric acid. 

 This chloride is dissolved, with evolution of hydrogen gas, in 

 a solution of pure potash; it produces tungstate of potash, and 

 chloride of potassium. With caustic ammonia, hydrogen gas 

 is also disengaged ; but in this instance a yellowish solution is 

 formed, which loses its colour : on being heated very slowly, 

 brown oxide of tungsten is deposited. 



This chloride seems to bear an analogy with the oxide, and 

 must be composed of. 



Atoms. 

 Chlorine .... 2 ... 26-79 

 Tungsten ... 1 ... 73-21 

 100.00 



The third combination of chlorine with tungsten, — on the 

 composition of which, however, I have made no experiment, 

 and on which I shall make no conjecture, — is generally formed 

 with the perchloride, although in very small quantity. I ob- 

 tained it once in a larger quantity on heating sulphuret of 

 tungsten in chlorine. This third chloride is the most beau- 

 tiful of any : it is formed in transparent needles of a beautiful 

 red colour, and often of great length ; it melts very easily by 

 » gentle heat, and crystallizes on cooling in long transparent 



radii 



