86 
vapour to be 148 (H = l), whereas the calculated density is 
171. On repeating this determination the numbers (1) 17T3 
and (2) 171'7 were obtained; whilst experiments made in 
mercury vapour gave (1) 17o - 8, (2) 170'S, proving that the 
vapour density of the monoxychloride is normal, and that 
the molecule of this substance contains 184 parts of metal. 
The Dioxychlorkle W0 2 C1 2 is best prepared by passing 
chlorine over the brown dioxide. Analysis gave 
Calculated. Found. 
Tungsten W = 64-32 64*1 1 
Chlorine Cl 2 = 24-31 24 - 74 
Oxygen 0 2 -lT37 
100-00 
The vapour density of the dioxychloride cannot be deter- 
mined at 440°, as at that temperature the contents of the 
bulb remains liquid. 
Bromides of Tungsten. 
Bromine vapour acts rapidly on hot metallic tungsten, 
forming dark bromine-like vapours which condense to a 
crystalline sublimate. Especial precautions require to be 
employed as regards exclusion of oxygen and moisture, as 
the oxybromide formed when these substances are present 
possesses very nearly the same colour as the bromide, and 
cannot be easily separated from the latter. 
Tungsten Pentabromide WBr 5> 
By the action of excess of bromine on tungsten a penta- 
and not a liexa-bromide is obtained. Prepared in this way 
the pentabromide forms dark shining crystals, having a 
metallic lustre not unlike that of iodine. These crystals 
melt at 276° and solidify at 273°, the liquid boiling at 333° 
(corr.) The pentabromide is at once decomposed by excess 
of water into the blue oxide of tungsten and hydrobromic 
acid, and immediately undergoes the same decomposition on 
exposure to moist air. On distillation, a small quantity of 
of a lower non-volatile bromide remains behind, and this 
explains the slightly too high percentage of metal found in 
the analysis. 
