82 
from a smaller one attached to it, according to the method 
adopted by the author in the determination of the vapour 
density of vanadium tetrachloride. The narrow neck of the 
bulb was kept open during the experiment b} f inserting a 
platinum wire, and after the sulphur or the mercury had 
been boiling for some minutes the neck was sealed. 
The results of three experiments in sulphur vapour at 
440° gave the density (H = l) as (1) 167'8, (2) 1097, (3) 
168’8. Two determinations in mercury vapour at 350° 
gave (1) 1907, (2) 19T2.* The fact of the alteration of the 
vapour density from 190 at 350° (closely approaching the 
normal density 198’5) to 167 at 440° shows pretty clearly 
that the anomalous vapour density is to be ascribed rather 
to dissociation than explained by Person’s suggestion of an 
error in the atomic weight; and this conclusion is fully 
borne out by further experiments detailed in the sequel. 
The residual chloride from the bulb possesses the same 
properties and composition as the original substance, there 
is no trace of free chlorine found in the cold bulb, nor does 
the colour of the vapour of the hexachloride change when 
it is strongly heated. 
On heating the residue with water, a difference between 
its behaviour and that of the original hexachloride can how- 
ever be detected, as the residue yielded an oxide which was 
perfectly yellow, but had a greenish colour, showing the 
existence of traces of oxides lower than W0 3 , although pre- 
sent in too small quantity to affect the analysis. 
In order to ascertain whether the gaseous hexachloride 
is decomposed at high temperatures, a portion of the pure 
chloride was distilled upwards in a current of dry carbonic 
acid for several hours. A continuous liberation of chlorine 
was clearly shown to occur, for, on passing the exit carbonic 
acid through a solution of potassium iodide considerable 
* Rieth has lately determined the vapour density of “ Wolfram Chlorid,” 
showing that its molecule contains 187 instead of 184 of metal, but there is 
nothing to show whether the substance thus examined was the hexa- or the 
penta-ehloride. 
