Scientia Sinica

No. | LU: VOLUME VISCO-ELASTIC TIHEORY OF FLUIDS . 41

Substituting (20), (21), Earl (27) into (18), we get

fan isl Cp C$? (w? +3, ) “~ pBr GC CpwttG CO oS

v

(32) giving v9 =V le Br =1/V By and v» =V yeo/e Br =1/V PBs ,

as they should. Disregarding intermolecular forces, we have Pr = 1 / ?, and (32) becomes

ize

P

(C+R) 07? +(C2tR) 0% | (33) Ca(C+R) w?+C (C2tR) w% |?

which agrees with the corresponding Kneser-Bourgin equation (see equation (19) in reference [7] and equation (12.1) in reference [6]). Using equation (31), we may express this in a still neater form:

P

e=2 (+R p

C+Ca w? Ts ) (34)

C2 -+ C2 w? ty

TV. Motrecutar STRUCTURE AND COLLISION PROCESSES

FROM GASEOUS COMPRESSIBILITIES

When either two of the following four quantities:

(1) Sound velocity at very low frequencies: Vos

(2) Sound velocity at very high frequencies: Dex

(3) Maximum absorption: Hm = (Om), (4) Dispersion velocity: v; = 0(@;).

have been determined, B) and B., the two limiting compressibilities, can readily be calculated. Furthermore, if, in addition, either , or ; is determined, t, and hence 7 can then. be calculated. In case the dispersion region is inaccessible, these quantities will have to be determined by accurate fitting to the observed part of the absorption or dispersion curve.

In the case of pure gases, only thermal relaxation can exist, and the knowledge of these quantities permits calculation of the heat capacities of the gas and also may provide us certain more definite information regarding the structure of the molecule and the characterities of the collision processes. Since it seems that these have not been fully recognized, they will be reviewed from the viewpoint of our theory in order to bring out how our theory may be directly applied to such investigations.