83 



quantities of iodine were liberated. The residual chloride 

 was tested for lower chlorides by titrating a weighed quan- 

 tity with a standard permanganate solution, which readily 

 oxidizes the blue oxide, formed by the action of water on 

 the pentachloride, into tungstic acid. In one experiment 

 thus conducted the residual chloride contained 3*3 per cent 

 of pentachloride, Avhilst in another no less than 24-6 per 

 cent of the pentachloride was formed. The pentachloride 

 treated in a similar way yields no free chlorine, and there- 

 fore does not undergo a similar decomposition at high tem- 

 peratures. 



2. Tungsten Pentachloride, WCI5. 



On distilling the hexachloride in a current of hydrogen a 

 reduction always takes place. If the temperature be kept 

 but little above the boiling point of the hexachloride, the 

 dark red colour of the vapour is seen to vanish, and a light 

 yellow coloured vapour makes its appearance, which soon 

 condenses into black drops or long shining black needles. 

 After two or three distillations in hydrogen a pure product 

 is obtained. Tungsten pentachloride crystallizes in long 

 black shining needles; if condensed in fine powder its 

 colour is dark green, and the powdered crystals also possess 

 a dark green colour like that of potassium manganate. 

 The pentachloride is exceedingly hygroscopic, the crystals 

 becoming instantly covered with a dark golden-green film 

 on exposure to air, and small particles being instantly con- 

 verted into drops. The crystals do not decrepitate Hke 

 those of the hexachloride. On treatment with larger 

 quantities of water the pentachloride gives rise to an olive- 

 gTeen solution, although the greater part of the chloride 

 forms the blue oxide and hydrochloric acid. Analyses made 

 with three separate preparations according to the method 

 already described, gave the following mean result : — 



Calcvilated. Found. 



Tungsten W= 184 50-89 50-90 



Chlorine Q\,= M1-5 49-11 48-58 



361-5 100-00 99-48 



