( 303 ) 
oe pen Ee 
Tar = C) ) ie Pak C's bs 
where 
Ties Dy 
—= 1—1.407+ 0.1822, ——=1-+4 0.526 « — 0.035 z?, 
then we find: 
a= —0.963 A= — 1.489. 
It appears therefore that much uncertainty exists about the 
values of « and (2. This must partly be ascribed to the uncertainty 
in the determination of 7,7 and pzz following the method of RAvrAu 
(from VERSCHAFFELT’s quadratic formulae I calculate for = 0.0494: 
Ty = 290.3° C., por = 68.35 atm, while VERSCHAFFELT found 
Tip = 287.8° C. and por = 68.1 atm.), and partly to the small 
number of observations, from which the variation of 7, and pj 
with z must be derived. 
However this may be, where the uncertainties in « and / are added 
to those in (2) and C4 ( HL Vit is obvious that nothing can be derived 
Or do OF 5 
from the comparison of the observations with the formulae (2a) and 
(2b). It is even easy to choose within the limits of uncertainty values 
2 
for df, (=), Cs ( ay ), that lead to results for = and 
av 
dw OT 
d, 
= ‘ , Which are entirely at variance with the observations. With 
. Oz 
the selection we made, as stated above, of (=) = br “and 
Tt 
027 ‘ 
C4 ( ) = — 322 we should derive by means of the values 
do Jz 
of « and (3, found from the quadratic formulae, in which VeRSCHAFFELT 
expressed his observations: 
a; A= ED: 
pe oh een OO 1 dppt _ 3 63 
Ty, de pk da 
which values might be made to agree with the form of the plait- 
point curve according to VERSCHAFFELT. 
