358 Mr Townsend, Electrical Properties of [Nov. 22, 



1 1 



per second, and the oxygen carrier at the rate of j—zr x — centi- 

 metres per second. 



The conclusions arrived at from the above investigations are 

 based on the assumption that in each case we are dealing with a 

 gas containing carriers all charged with the same sign, either 

 positive or negative. Experiments on conductivity have been 

 carried out in order to test this point, and it has been found that 

 we are in reality dealing with mixtures. Thus in the case of 

 oxygen, or hydrogen, from a sulphuric acid cell having a positive 

 charge equal to 3e, it is possible to obtain from the gas a positive 

 charge of 4e and a negative charge of e. If we suppose the positive 

 and negative to act independently the charge on the oxygen 

 carrier would be 510~ 10 instead of 310 -10 ; also the velocities under a 

 volt per centimetre would be smaller in the ratio of 3:4 than 

 those given above. 



We can arrive at an approximate value to the size of the 

 carrier if w x e assume that the viscosity of a gas effects the motion 

 of a small sphere and a large one according to the same law 



67TfiaV=P. 



(Lamb, loc. cit). Substituting 



for hydrogen, and 



F =30oVe-' i = 10 " 



P = — x - 10 -10 = - 10 -12 

 r 300 2 LU 2 U ' 



we get the radius (a) for the hydrogen carrier 4*5 10 -7 . Similar 

 substitutions give the radius of the oxygen carrier 1210 -7 . Hence 

 the carriers are large compared with molecular dimensions. 



The velocities obtained for the carriers in the conductivity due 

 to Rontgen rays are far greater than the above. Thus for oxygen 

 and hydrogen Mr Rutherford obtains velocities of 5 2, and 1*4 

 centims. per second under a volt per centimetre. [Phil. Mag., 

 Nov. 1897.] 



If we assume that the charges on the carriers are of the same 

 order as those obtained in § 7 we see that the dimensions of the 

 carrier are smaller than those with which we are here dealing. 



