Scientia Sinica

44 SCIENTIA SINICA Vol, V

! Table II* eee

Gas or vapour Hg SF, CS_ CoH, Temp. °C 36.5 36.10 45 90

p (10-* gm/cm®) 0.080 3.74 (2.91) 2.75 etal vq (m/sce) 1336 138.5 202.0 200.0

pains) 1460 153.4 >216.0 208.0

Bo (10-7 cm?2/dyne) 7.00 9.08 8.43 9.09

5, ) Bo (10-7 cm®/dyne) 5.87 Final <7.36 <8.40

Cal 1.41: 1.09 it? 1.69

Jo 1.68 1.34 21.35 21.18 Exp’tal c;/2m (10°c/sec) ~8 0.39 ~0.45 ~0.45—

T, (10-7 sec) ~0.15 4.4 ~8.2 ~3.8

Gr (elimnole) 6.85 24.1 13.7 24.1 Calc’d ;

G; (cal/mole) 2.7 16 6.0 i

Th (10-7 sec) ~0.25 10 ~15 ~7

SS of Chemistry and Physics (the one in. parathesis is calculated from the molecular weight). The dispersion data for hydrogen are those of Zartman”), yielding results in agreement with those of Table I. The data for SF, are those of O’Connor!™!; they yield y,=4/3 indicating also that all six degrees of freedom, translational and rotational, respond to pressure change immediate_ly. The data for CS, and C,H, are those of Railston!3!, The value of y., for C.H¢ indicates that only a portion of the vibrational degrees of freedom is responsible for the observed relaxation, the remaining portion being also able to respond to pressure change immediately”. The latter type of result has never been reported and consequently it is desirable to check Railston’s data by further experiments.

V. DERIVATION OF LIEBERMANN’s EQUATION OF Sounp ABSORPTION IN. SOLUTIONS FROM

VoLuME Visco-ELastic THEORY

In the case of chemical relaxation, on account of the slow rate of chemical reaction, the time required to establish chemical equilibrium may be and often is larger than that required to establish thermal equilibrium. Hence, as mentioned in § I, in such a case we have to distinguish the instantaneous and static isothermal compressibilities, B; and f°. Here, B; refers to compression at a rate that is very fast relative to the slow chemical change although

*Formulas used same as in Table 1 except Bo=1/pv%, and =7,,/T) @;.

In the case of CgHg we have also used van der Waals and Berthelot equations of state to calculate Br. The results make Y larger than that-given in -Table II by about 2 and 3 per cent respectively. Thus, consideration of deviation of the vapour from being ideal does not make this result disappear.