pressure at 473°, till the vapour pressure line which had been found 
before with preparation N°. 4, had been reached, but then the expe- 
riment would certainly have been continued for several hours, which 
gave rise to difficulties. To reach our purpose more quickly, the 
experiment was finished, and part of the same preparation N°. 4a, 
with which now a too low vapour pressure had been found, was 
heated with 0,15°/, Iodium at 410° for five hours, and then again 
subjected to the known after-treatment with CS,. Finally the vapour 
tension of this preparation N°. 45 was once more determined with 
the glass spring N°. 77 and then a vapour tension line was found 
which up to 450° perfectly coincided with the curve N°. 74, which 
had been found with the same material before the internal equili- 
brium had been disturbed. *) 
This experiment has, therefore, shown in the most convincing way 
that for violet phosphorus we have to do here with an internal equi- 
hbrium between at least two pseudo components, which greatly differ 
in volatility. 
3. Designation of the unary stable solid state of the phosphorus, 
and the nature of red phosphorus. 
Our investigation has taught us that there is only one stable solid 
modification, and it is now the question by what name this modifi- 
cation will be denoted. In not very finely crystallized condition the 
colour of this stable solid state of the phosphorus is violet. If this 
substance is rubbed fine, however, the colour becomes dark red, 
and the greater the fineness, the lighter the colour. In the same 
way of preparing preparations of different colour are often obtained, 
which, however, had entirely to be ascribed to a difference in 
fineness, for it always appeared that though the colour was different, 
the preparations had the same vapour tension. 
In virtue of this the name of violet phosphorus naturally suggests 
1) It should be noticed that when iodium is added to the solid red phosphorus, 
only a superficial internal equilibrium is obtained. If the vapour tension of the 
obtained solid substance is determined, the case can therefore occur that the vapour 
tension begins to deviate from the accurate curve at a definite temperature, in 
consequence of this that the quantity of the most volatile pseudo-component present 
has become insufficient, and the velocity of the internal conversion is not great 
enough to supply the quantity that is lacking. This case was temporarily met with 
in the above-mentioned experiment above 450°. Above this temperature somewhat 
too low pressures were namely found, but if the temperature was kept constant 
for half an hour, a rise of the pressure occurred again. 
