84 
Tungsten pentachloride melts completely at 248° C. and 
solidifies at 242°; the boiling point is 275°'6 (corr). The 
vapour density of this chloride taken in sulphur vapour at 
440° was found to be (1) 186 - 4, (2) 186-5, (3) 185’7 ; the 
normal calculated density (H = l) being 180 - 7. 
Hence the molecule of pentachloride contains one atom 
(W=184) of metal. 
3. Tungsten Tetrachloride WC1 4 . 
The tetrachloride forms the nonvolatile residue produced 
in the distillation of the hexachloride in hydi'ogen. In 
order to obtain it in a pure state the mixture of the two 
higher chlorides is distilled at a low temperature, (best in a 
bath of melted sulphur,) and in a current of dry hydrogen 
or carbonic acid. The tetrachloride is a loose soft crystal- 
line powder of a greyish brown colour. It is highly 
hygroscopic, but not so much so as the pentachloride, and 
it is partially decomposed by cold water into brown oxide 
and hydrochloric acid, forming also a greenish brown solu- 
tion, which is rather more stable than the green solutions of 
the pentachloride in water. The tetrachloride is non- 
volatile and infusible under ordinary pressure, but it is 
decomposed on heating into pentachloride, which distills 
off, and a lower dichloride which remains behind. On 
heating in hydrogen at a temperature above the melting 
point of zinc, the tetrachloride is reduced to metallic 
tungsten, which is sometimes deposited as a black tinder- 
like mass, undergoing spontaneous ignition on exposure to 
the air. 
Analyses of four portions gave the following mean 
numbers : 
Calculated. 
Found. 
Tungsten 
GO 
r-H 
II 
£ 
.... 56-45 .... 
.. 67-22 
Chlorine 
Cfi - 142 .. 
.... 43-55 .... 
.. 42-24 
326 
100-00 
99-46 
4, Tungsten Bichloride, W CLj. 
This body is formed in light grey crusts on reducing the 
hexachloride at high temperatures. It can be best prepared 
