178 
Dr. Thomson on some of 
were made to determine the composition of phosphuret of 
chromium will be readily understood by the reader. 
3*2 grains of phosphorus and 5- 08 grains of anhydrous 
green oxide of chromium were put into a green glass tube, 
shut at one end and open at the other. The phosphorus 
occupied the bottom of the tube and the oxide the middle 
portion, extending about two inches, and distant rather more 
than one inch from the phosphorus. The tube was laid 
horizontally across a choffer, and the portion of it containing 
the green oxide was raised to a red heat by means of a 
charcoal fire. The phosphorus was then sublimed through 
the green oxide by means of a spirit lamp. A brilliant 
combustion took place, and the oxide was converted into 
phosphuret of chromium. 
The phosphuret thus formed still continued an incoherent 
powder. It had a brown colour, was tasteless, and insoluble 
in water and acids. Before the blow pipe it was agglutinated 
together, but did not undergo complete fusion. It weighed 
6-21 grains. 
5*08 grains of green oxide of chromium are equivalent to 
4 0 65 grains of chromium. Hence, the phosphuret was a 
compound of 
Chromium - - 4*065 or 4 
Phosphorus - - 2*145 or 2*11 
atom phosphorus weighs 2*25, which comes near 2*11. 
The compound thus seems to consist of 1 atom of chromium 
united to i\ atom phosphorus. It is therefore a sesqui- 
phosphuret. 
I digested this phosphuret for a week in nitric acid. No 
solution took place, but the matter assumed a fine green 
