344 



case starling from Maxwell's hypothesis'), that llie irioleciiles iriaj 

 be looked upon as centres of force which repel each other with a 

 force proportional to r~^. In this wa}' he fonnd 



15 2 -a 



''■'^27.-^ <^" 



In these tormulae ;., represents the mean free path as determined 

 in Clausius's theory, therefore: 



If the mean free path, as found by 0. E. Mkyeh's') method of 

 calculation, 





1 



is introduced into formula II, we find 



2 



y/). — 2.32 



2a 



^ 2. In a paper') which has appeared in the Annalen der Fhysik and 

 to which the readei' may here be !-eferred, the absolute value of the 

 heat-conductivity at 0° C, K^, has been investigated for a number 

 of pure gases. In the experimental determinations Schlkiehmachkk's') 

 method was used modified in such a manner that it was possible 

 to eliminate the influence of convection on the heat conduction. 

 Siiuultaneously the value of the temperatui-e-drop at 0° C. was 

 determined for the same gases and an excelleut agreement was 

 found between the experimental value and the one calculated from 

 formula II, if for a the results obtained by Knudsen "*) were used. 

 Amongst the gases experimented on was the same distilled neon, 

 with which the present experiments were made. 



The result of the measurements for neon was 



k\ = 0.000 1 0890 ^(/r. cal. (/rad. sec. cm. and //, — 2.391. 



For pure neon and bright platinum Knudsen found a = 0.653, hence: 



•//; ^ 2.32 . — 



-a 



1) J. Gl. Maxwell. Scientific papers Vol. II, p. 23. 



') E Meyer. Kinet. Theorie der Gase p. 111. 



It makes no difference whether Meyer's calculation or a different one is followed 

 here, seeing that the factor which has a different value in the various results 

 drops out from the final result by the introduction of the pressure. 



8) SoPHUs Weber Ann. d. Ph. (4), 54, (1917), p. 342. 



^) A. ScHLEiERMACHER. Wied. Ann. 84, (1888), p. 623. 



6) M. Knudsen. Ann. d. Ph., (4) 4(i, (1915), p. 641. 



