84 PROF. H. E. ROSCOE ON CERTAIN 



This conclusion is fully borne out by further experiments 

 detailed in the sequel*. 



The residual hexachloride remaining in the bulb exhibits 

 the same properties, and analysis shows that it possesses the 

 same composition (see Analysis No. VI.) ,as the original sub- 

 stance ; and there is no trace of free chlorine found in the cold 

 bulb, nor does the vapour of the WC1 6 appear to change its 

 peculiar dark red colour at any higher temperature to which 

 it was exposed even when mixed with chlorine or carbonic 

 acid. On treating the residue with water, a difference 

 between its behaviour and that of the original hexachloride 

 could, however, be detected, as it yielded an oxide which 

 was not perfectly yellow, but had a greenish colour, showing 

 the existence of traces of oxides lower than WO p although 

 present in too small quantities to affect the results of the 

 analysis. 



In order to ascertain whether the gaseous hexachloride 

 is decomposed at high temperatures, a portion of this chlo- 

 ride was distilled upwards for several hours in a current of 

 dry carbonic acid. A continuous liberation of chlorine 

 was clearly shown to occur by passing the exit gas through 

 a solution of potassium iodide from which considerable 

 quantities of iodine were set free. The residual chloride 

 was tested for lower chlorides of tungsten by titrating 

 a weighed quantity with standard permanganate, which 

 readily oxidizes the blue oxide formed by the action of 

 w r ater on the pentachloride into tungstic acid (W a 5 + O 

 = 2WOJ. 1*2237 grm. of the residual choride deco- 

 lorized 0*7 cub. centim. of a standard solution, of which 

 1 cub. centim. corresponds to 0*001278 grm. oxygen. 

 This quantity is required for the conversion of 0*0404 



* E. Rieth (Ber. Deutsch. Cliem. Gesellscbaft, 1870, p. 666) determined 

 the vapour-density of "Wolfram chlorid," showing that it contained 187 

 of metal instead of 184. There is nothing to prove whether the body thus 

 examined was the hexa- or pentachloride. 



