Scientia Sinica

No. 1 LU; VOLUME VISCO-ELASTIC TIHEORY OF FLUIDS 43

results are also obtained from the dispersion data as given in Table II. These “two values permit us to say that there is ‘relaxation of the two rotational degrees of freedom and that while rotational states are excited there is practically no transition in the vibrational state. This is reasonable since we know that the transition energy between the two lowest rotational states of H, corresponds to a temperature as low as 171° K whereas the excitation energy of its vibrational level corresponds to a temperature as high as 6140°K"". The absorption data for the triatomic gases are those obtained by Fricks''*! under the atmospheric pressure. CO, N2O, and CS, all give y, =7/5, indicating that the three translational and apparently only two rotational degrees of freedom respond to changes of pressure immediately while the vibrational degrees of freedom give rise to relaxation. This shows a linear structure for these molecules. In the case of SO,, y., = 4/3, indicating that all six degrees of freedom, translational and rotational, respond to the pressure change immediately. This shows that SO, is a non-linear molecule. All these conclusions regarding molecular structure are in agreement with those established from the infra-red and Raman spectroscopic and electron diffraction data.

In Table II are tabulated the results of calculations from the ultrasonic dispersion data. In this table only the value of ¢ is taken from the Handbook

Table I* a Gas or yapour Hos CO, N,O CS. SO2 an

Temp. °C 25 -25.63 23 23 23 23 Exp’tal Le 0.50 0.75 0.230 0.296 0.406 0.149 Gale’d v.,/v 1.08 1.12 1.038 1.048 1.066 1.024 Exp’tal p (10-$ gm/cm®) 0.083 0.080 1.81 1.81 @sisye 2.68 Exp’tal vo (m/sec) 1310 1336 269.7 270.9 202.8 217.6 Cale?d By (10-7 cm?/dyne) 6.9 7.0 Te29 Teo3 Mell 7.88 Cale’d B.,(10-* cm?/dyne) 529 5.6 7.05 6.86 6.84 feat Cale’d Yo 1.4 1.4 1.30 1.32 1.28 1.26 Cald’d T. Ley 1.8 1.40 1.44 ea, 1.32 Exp’tal @y;/27(kc/sec) 10 x 108 10 x 108 20 153 379 1040 Cale’d T. (10-® sec) 0.017 0.017 8.26 1.09 . 0.450 0.157 Cale’d Cp (cal/mole) 7.0 7.0 8.62 8.21 9.10 9.26 Cale’d C; (cal/mole) Dail DD ey ile) Dei, 1 Cale’d T4 (10-° sec) 0.02 0.03 2) iAGe 0.63 0.2

*Formulas used in calculations:

Yn _ Lm sn \" _ 4 _ Yoo \* Uo ~ OR +jie(2y. Bo=1/p%, pe = Bi/( =),

if To To. =1/Bo?P, To. =1/B p, ta ee 7 > ; a ; ToR (T2—T.) R Gy Cp = > C= SO = Lo oe Ga = Ge=1) =D rp

**Calculated from the molecular weight.