451 



c 



1 H 



273 ri, 

 0.00139 —k^ 



1 + -. ^^' 

 dp 2' 



^ ' c \ T ' 



273 J*^ 



The meaning of the symbols is the same as in Knudsen's paper. 



According to the theory the constants l\ and k^ are independent 



of the nature of the gas. Experimentally this formula has been 



confirmed for hydrogen and oxygen, and ^, and k^ appear actually 



to be independent of the nature of the gas. The equation which 



may be integrated in a fairly simple manner loses its validity for 



2R 

 small values of— . For carbon dioxide the formula w^as used with 



A 



the values of k^ and k^ which were found from the measurements 



with hydrogen and oxygen. As shown by Table II the numbers 



under I corr. and II corr. agree well with each other wdiich may 



be looked upon as a partial confirmation of the underlying suppo- 



dp 

 sitions. Fig. 3 gives a graphic representation of —r, according to tiie 



different formulae. The abscissae give the pressures in baryes, the 



dp 

 ordinates —^^ for the tube with 2 /t* = 0.563 cm. Curve 1 represents 

 dT 



the relation according to formula /. For the corrections the formula 



2R 

 has not been used, when ^— <^ 10 ; it depends, however, on the 



degree of accuracy required, where the limit has to be taken. 



272 

 (2).^<l. 



dp 



In this case the followring formula was used for — : 



^ dT 



where p and A are connected by the relation p.>l = const.; this 

 constant is determined by the viscosity corresponding to the tempe- 

 rature T. 



29* 



