1919.] The Sixth Indian Science Congress. exi 
conception of imponderables was foreign to the prevailing 
scientific belief, Maxwell’s pronouncement on the intimate 
fluid, there is , as yet, no experimental evidence to show whether 
the electric current is the current of a material substance or a 
double current or whether its velocity is great or small.” 
had, in fact, > i to measure the inertia of electricity but 
without success. Evidently, a more refined process was 
necessary as that which he employed. This has now been 
accomplished and we now know that: the unit charge of electri- 
city is about 4'5 x 10-'" electrostatic unit, the unit of negative 
charge, having a mass of about 8°8 x 10- 38 gramme (under the 
conditions of the experiment for its determination), while the 
unit of positive oe has a mass, comparable to that of an 
ordinary material atom. 
The postulate of an absolute unit of charge is, in fact, 
implicitly contained in the statement of Faraday’s laws of 
a 
ode, 
It is, a priori, evident, therefore, that this is the smallest 
quantity of electricity that takes part in electrical phenomena 
and has, therefore, as Helmtolz pointed out in 1880, the 
characteristics of an atom or absolute unit of electricity. 
Measurements under this and other conditions have established 
its identity as an invariable change. And, if we call it the 
electron, we must conceive an atom showing no electrical pro- 
perties as the result of combination of one or more electrons 
with what may fittingly be called a certain number of positive 
particles. This would then amount to the statement that elec- 
a Pore phoresis rays, which follow a straight path, n 
