to Mr. BripGMaN for a small quantity of his black phosphorus, 
which request was complied with the greatest readiness. 
As the black phosphorus contained carbon, our first work was 
to remove this carbon, which was attained by pounding it fine and 
then washing it with: water 5. Then the black phosphorus was 
extracted in a Sohxlet-apparatus with CS, further washed with 
alcohol, then with an aqueous solution of ammonia, and finally 
dried in vacuum over P,O, 
With application of the same method, in which the vapour pres- 
sure of the violet phosphorus was determined, the vapour pressure 
of the product thus obtained was measured, in which it appeared 
that the purification described here was perfectly inadequate to 
remove the kerosene from the black phosphorus, which substance 
had been used by BRIDGMAN as pressure-liquid. 
It appeared namely, that already at 300° C. a gas escaped, in 
consequence of which within half an hour the pressure had become 
2 atmospheres higher than the vapour tension of the violet phospho- 
rus at this temperature. 
In order to expel as much as possible the kerosene evidently 
dissolved in the black phosphorus, the substance was conveyed into 
a vessel of the form as given in tie. 1. 
Q 
Fig. 1. 
The black phosphorus was put in the globe a, after which the 
tube d was fused to. Then the tube c was connected with the 
Gaede-pump, and the apparatus was exhausted. After this the 
apparatus was placed in an air bath, the temperature of which 
was gradually raised to + 260° C. This heating had to take place 
slowly, as otherwise the powdery black phosphorus would fly 
away for the greater part in consequence of the quick generation 
of gas, and would get into the pump. By arranging the apparatus 
as described here, we ensured that when any flying up took place, 
the phosphorus blown from globe « got into globe 4, and remained there. 
The first preparation was heated up to 260° C. in the way described 
here for a day, during which part of it of course evaporated, and 
deposited in the form of white phosphorus in that part of tube 
ec which was outside the air bath. 
1) The black phosphorus thus obtained melted without any residue to a colour- 
less liquid. 
