275 
assumed critical temperature (1427° C.), viz. in the empirical Jaw 
that below 7, (not immediately below T,, however, where 
D—D,:..V1—m), the equation 
i) ks En 
holds in approximation, so that (D,—D,)* is proportional to 1—m, 
ie. to 7,—T (n=T: T.). Now we get the following table 
1000° | 1100° 1200° | = 1300° 1400° 
D-D;= | 10,0 Od | Areas 6,15 (3,40) 
(D:—D,)3= | 1000 754 484 233 (39) 
so that the four first values of (D,—D,)* are roughly to each other 
as 4:3:2:1, which would give the value 1400° C. for 7%. 
The corresponding values of (D,—WD,)? are to each other as 
100: 83:62:38 (:11,6), ie. as 5:4:3:2 about, which would point 
to T,=1500°C. And as (except close to 7.) the B~-law is sooner 
fulfilled than the P~-law, 7, will lie nearer to 1400° than to 
1500° — in concordance, therefore, with our assumption (1427°). 
A critical temperature higher than 1500°, as would follow from a 
few values recorded by Miss Benprr, is in my opinion in conflict 
with her own observations concerning D, and D,. When the two 
last values of (D,—D,)*, viz. 38 and 11,6 are taken as criterion of 
the ~-law, holding theoretically near 7, then the value of about 
1440° C. would follow from this for 7. 
Let us now examine the (reduced) coefficient of direction of the 
so-called straight diameter. For the total course between the absolute 
zero and the critical temperature evidently 2 (1Q—y) = 14,28:4,15= 
= 3,44 is found, hence 1+ y—1,72, y=0,72. But this amount 
can only be assigned to the last piece between 1000° C. and 77, 
where — in consequence of the increasing association in the vapour- 
phase — the straight diameter after its almost linear course between 
— 40° and + 1000° C. suddenly begins to show an appreciable 
curvature towards the side of the large volumes. 
As regards the said part below 1000° (where the vapour phase 
is still absolutely without influence), we find there e.g. between 0° 
and 300° C.: 
13,5956—12,8792 1700 
iio ETC. eS VEA 
300 4,15 
== 0,9782, 
hence y = 0,489 = 0,49. 
