( 869 ) 
A = 00036618 t \ 
1 
10° BD = 168-982 : — 435°381 — 722-848 — + 
t 
1 
1 
+ 420-696 — — 118-456 — 
t {is 
3 
1 
10" § = 50-3923 t + 181-386 + 131-2531 — + (16) 
: l il 
+ 199-2748 Foci 50°6347 a 
1 
Lov Ss) — 424-680't — 131-462 —- 905004 = aa 
1 1 
+ 367-7055 qa 7 1785625 = 
The values of the critical constants used in the reduction were 
pk = 15 atm. and 7), = 29° abs.; but as the reduction is ultimately 
reversed the accuracy or otherwise of these constants is immaterial. 
The Wirpemayn value of C, == 3.41 cal. has been used. An estimate 
of the change of C, with temperature was obtained by combining 
equation (2) with the well-known thermodynamical relation 
_ Op ov 
C, —(=T — — 
OT, OT, 
and regarding C, as independent of the temperature. *) This showed 
that down to —190° C. the variation in C, at 1 atm. was less than 
1°/,; hence it appeared that a sufficiently high degree of accuracy 
was reached by retaining the constant value 3.41 throughout these 
calculations. 
For the calculations four terms of equation (2) were found suffi- 
cient, for the greatest influence of the D-term on the values shown 
in Table | of 7—7, at 100 atm. pressure was not greater than 
0°.15. Table 1*) contains the results of the calculations; from it has 
been constructed the series of (7,—T,, py—1)7=const, Curves shown 
in fig. 1 and also the series of (7,—77, T1)p,=const. Curves of fig. 2. 
El 
') Cf. A. W. Wrrkowskr: Bull. de Acad. d. Sciences de Crac. Oct.-Nov. 1895. 
The comparatively great change of Cy and C, with temperature deduced by 
H. re Crarevier and E, Mautarp. (Séanc. Soc. de Phys. p. 308. (1888)) from ex- 
periments at high temperatures cannot be applied to low temperatures without 
further investigation. 
?) The calculation is not extended beyond the limits of density at each 
temperature at which powers higher than those occurring in (15) must be taken 
into account, 
