Thermal Conductivity and Viscosity oj Gases, 53 



equal to unity, the equation, with an appropriate value of the 

 constant, quite well represents the experimental results with 

 the exception of those for the monatomic gases. This leads, 

 in the case of perfect gases, to the simple relation 



myk 



— - — = constant, 

 Vo 



where m is the molecular mass. 



In the following table, with the zero temperature measures 

 of k and n, taken from Eucken's paper, L give, for the cal- 

 culation of /, the experimental results for c p and 7 instead 



Table I. 



1 







3 



4 5 



6 



Molecule. 



m. 



£ xl0 6 . 



»7 Xl0 6 . c p . 



r- 



He 



4 



40 



2 

 28 

 32 

 29 

 71 

 28 

 30 



34 



336 

 39-0 



397 

 56-6 

 57-0 

 56-6 

 18-29 

 54-25 

 55 5 



30-45 



33-7 



35-15 



19-5 



16-15 



51-35 

 440 



71-45 



40'7 

 42-6 



187 6 1-260* 

 210-2 : 0-123 



85 1 3-422t 

 167-6 i 0-2429t 

 192-2 ! 0-2173f 

 171 i 0-2376t 

 123-7 0-115 

 167-2 0-2502* 

 179-4 ! 0232 



118-4 0-245 

 138 1 0-2010 

 136-2 1 0-213 

 1183 J 0-1544+ 

 924 | 0160 



92-6 j 0-520 

 94-3 



102-9 0-591 



90-66 0404 



85-5 



163 

 1-667 



l-402t 



l-412t 



1-4021- 



l-405t 



1-323| 



1401 



1-394 



1-340 

 1-300 

 1-324 

 1-256 

 1-239 



1-336 

 1-26 



1-313 



1-264 

 1-22 



A 



B~ ... 



"2 



N, 



o 



Air 



CI, 



CO 



NO 



H,S 



C0„ 



N 2 



44 

 44 



64 



76 



17 

 26 



16 



28 

 30 



S0 o 



cs" 



NE, 



C H 



CH 4 



C H, 



C,H n 





* Scheel and Reuse, Ann. d. PkysiJc, xl. 3, p. 473 (1913). t Escher, Ann. d. 

 Physik, xlii. 4, p. 761 (1913). \ Landolt-Bornstein Tabellen. All other values 

 in columns 5 and 6, from Kaye and Laby's Tables. 



of the values of c v . The figures given for / in column 2 of 

 Table II., deduced from the equation k=frjc p /y, are thus 

 wholly dependent on the results of experiment. 



In this second table, the values of /, derived from the 

 expression f=7'32(y— IJ/y 1 ' 3 , are entered in column 3. An 

 idea of the physical accuracy of the calculated results may, 

 therefore, be obtained from a comparison of these figures 



