80 
with the corresponding bromine and iodine compounds, 
appeared before all things necessary. 
The author then describes the mode employed for pre- 
paring pure metallic tungsten, which was found to possess 
a spec. grav. of 19'261 at 12° C. 
The Chlorides of Tungsten. 
1. Tungsten Hexachloride, WC1 6 . 
For the preparation of this chloride in the pure state it is 
absolutely necessary to exclude every trace of air or moisture. 
For this purpose the metal must be burnt in a current of 
perfectly dry and air-free chlorine, otherwise red oxychloride 
is formed, and this cannot be separated from the chloride, 
owing to the slight differences in their boiling points. 
Metallic tungsten takes fire in chlorine at a moderate 
heat. On heating the tube containing the metal a granular 
sublimate of dark violet opaque oystals of the hexachloride 
makes its appearance, which, when prepared in quantity, 
collects as a dark blackish red liquid. In order to purify it 
this liquid is distilled several times in excess of chlorine, 
and then slowly rectified in a stream of hydrogen, by which 
means any traces of adhering oxychloride can be got rid of. 
The dark violet coloured crystals decrepitate on cooling, 
and the mass falls to a crystalline powder. When pure the 
solid hexachloride does not undergo any change, even in 
moist aii', but in presence of the smallest trace of oxychloride 
it at once absorbs moisture, evolving fumes of hydrochloric 
acid, and changes from a violet to a brown colour. Cold 
water also acts very slowly on the pure substance, but, 
if impure, the mass is at once decomposed by cold water into 
a greenish oxide. The hexachloride is readily soluble in 
carbon disulphide, from which it is deposited in hexagonal 
plates. On several occasions the tubes containing the crys- 
talline chloride exploded on opening them with a file, the 
crystals suddenly assuming the form of the decrepitated 
substance. 
