180 



THE ROYAL SOCIETY OF CANADA 



and dry air. The following values were obtained for the exponent n, 

 in the formula 



= Mo I ) . 



\273.1/ 



those in the second column of the table, were obtained by the writer; 

 those in the third column are added for comparison. They are taken 

 from Jeans' "Dynamical Theory of Gases" (2nd edition). 



It will be seen that the present determinations agree fairly well with 

 previous ones, so that the method appears feasible, although the 

 apparatus is very small. A determination of the viscosity of air, from 

 the measured dimensions of the apparatus gave the result 



/x= 184.0X10"'^ at 23.0° O. 

 Probably the best determination of this quantity, gives the value^ 

 M=182.26XlO~*'at 23.0° C. 

 In conclusion, the writer desires to express his thanks both to 

 Dr. King, for suggesting the problem, and for assistance while the 

 work was being carried out, and to the Advisory Council for Scientific 

 and Induslrial Research under whose auspices the experiment was 

 undertaken. 



McGill University, 

 May 12th, 1919. 



iLord Rayleigh, Proc. Roy. Soc, LXVL, p. 68. 



^Von Obermayer, Wiener Sitzungsberichte, LXXIII. (2), p. 433. 



'Harrington, E., Physical Review, December 1916. 



