309 
With regard to the critical temperature we saw above that phos- 
phorus there answers pretty well to formula P,. For 47 = 535 . 10 
was namely found instead of the theoretical value + > 140 .10-5, 
from which 77 == 3,82 would follow ’). 
Accordingly we have for the yellow phosphorus (also az will be = a,): 
WN == Osi A= 9,02, 
whereas the following equation holds for the red phosphorus : 
' 
at € ; 
Dm en a oy 
NJ: ; 
The accurate value of lies, therefore, probably in the neigh- 
bourhood of 5*/,. 
Le == 9.24, 
| When we examine the values found for 5, Se, and Te in the 
same light, we shall have to bear in mind with regard to the last 
elements that on account of the dissociation into isolated atoms the 
attraction at 7% will be another than at the triple point. 
For Sulphur the molecular formula is probably S3 at 7% (see 
above), that at 7 being S, for both modifications. Hence 7, will 
be = 8, nz =—6,3 in (1),: so that n,:nze becomes = 1,27, and the 
value of @ will now become — 4,28 X 1,27 — 5,4. 
For Selenium nr == 2: (A + nz) = 2: 1,32 —= 1,52, but at the triple 
point , will probably be — 67). We find, therefore, 3,96 for the 
ratio. 7, : 7: Further a,— 7,1.10-7, VKar=14,3..10-?, hence 
a, : dp = 0,247, so that fu, must finally be multiplied by 0,98. 
Accordingly the value of y would become — 4,85 here. 
Por? efherume nj 2 AF Oe 22 ny = 6s henee'n,; ag = bd. 
But} a,-is-about 940,22: Diaz == 25,5 4072, hence, nr == 0,125, 
We must therefore multiply by 0,669, through which 7,10 passes 
into 4,75. 
Except for O,, where p — 8,85 (possibly also oxygen is associated 
at the triple point, up to e.g. 7, — 2,5, which would render p — 4,8), 
we find, therefore, after due correction everywhere a value in the 
neighbourhood of 5 for the triple point ratio w,—b,):v,. 
1) According to PREUNER and BROCKMÖLLER (loc. cit.) the dissociation constant 
(at 1 atm.) of the reaction P,— 2 P, is still slight even at 800° C., which will, 
therefore, be the case in a much greater degree at a pressure of 83 atm. At 
800° ©. ¢32:¢,=0,00855:p holds for this reaction, i. e ¢,?:¢,=0,0001 with 
p = 838, which gives c,=0,01. when c, is near 1. [For the reaction P, —> 2P, 
we have ¢?:¢,; =0,000046:p, so that ¢,2:¢, becomes = 0,00000055 for 83 atm. 
hence cj = 0,00074, referring to cz = 1). 
2) In analogy with sulphur also Seg-molecules will probably be present at low 
temperatures. 
