232 Prof. A. Schuster or Electric Inertia ani 



may calculate 2m' = p/W. Taking p = q X 10~ 5 , N' = 21 x 10 18 , 

 we'find m' = 2 x lO" 24 , and hence q = 2 X 10~ 20 *. 

 Also 



a= -3. . £ = ? x 2 x 10" 20 x 1-3 x 10 7 = 1'8 x 10~ 13 . 

 6 m 6 



The linear dimension of the electron would therefore have to 

 he ahout thirty-thousand times smaller than the molecular 

 distance in solids, but I can see nothing more astonishing or 

 improbable in this than in the alternative assumption of 

 particles having masses thirteen-hundred times smaller than 

 the masses of hydrogen atoms. 



The electric energy per unit volume and unit current 

 density was found to be l/3aN, which in the case of solid 

 conductors would therefore become 2 x 10~ 12 C.G.S. units. 

 We po-sess fortunately a series of experiments by Hertz in 

 which he investigated the possibility of electric inertia, and 

 found that if it exists it must be smaller than 18 X 10~ 8 for 

 unit current-density and unit volume. The effect we have 

 calculated is much smaller than the number given by Hertz, 

 and as this represents the limit beyond which he could not 

 push his experiments, we must for the present give up the 

 hope of testing the results of our theory. There seems only 

 one chance — and not at all an impossible one- — that in some 

 cases the effects maybe considerably larger than those calcu- 

 lated above. Perhaps in some bad conductors like carbon, 

 the distance between the moving electrons is greater than the 

 distance between the molecules. If it is fifty times as great, 

 we should get within the limits to which Hertz worked. 



7. In the case of electrolytes the electric inertia of moving 

 ions is small compared to their mass inertia. The latter must 

 to some extent affect the motion of electricity in electrolytes, 

 and it becomes a matter of interest to obtain, if possible, 

 some experimental evidence to establish the effects of this 

 mass inertia. 



If N molecules of a dissociated suit are dissolved in unit 

 volume of water, and if w 1? u 2 represent the velocities of the 

 ions having masses m 1? m 2 , the energy per unit volume is 



JN (W|Mj 2 + m 2 u 2 2 ) . 

 If the masses of the ions contained in each molecule referred 

 to hydrogen are a 1? a 2 , and a represents the ratio between the 

 mass and charge for a hydrogen atom, which is numerically 

 equal to 104 XlO" 5 , 



m 1 = a 1 xq, m 2 — a 2 aq. 



* Owing to some arithmetical "bluuder, this quantity was put down as 

 3xl0~ 23 in my Bakerian Lecture. 



