96 UNIVERSITY OF MISSOURI BULLETIN 



per second on a given area can be counted by means of a 

 microscope. 



"It has been shown that the number of scintillations de- 

 termined in this way is equal to the number of impinging a 

 particles when counted by the electric method. This shows 

 that the impact of each a particle on the zinc sulphide pro- 

 duces a visible scintillation. There are thus two distinct 

 methods — one electrical, the other optical — for detecting the 

 emission of a single a particle from radium." 



The number expelled per gram of radium was 3.4 x 10^^ 

 or 34,000,000,000 per second. 



On an average out of 125,000,000 a particles fired from the 

 source only about one communicates an impulse to the needle 

 of the electrometer when this is used as the detecting instru- 

 ment. 



"In 1836 Dumas said: 'La chimie coupait les atomes que 

 la Physique ne pouvait pas couper. Voila tout.' Now the 

 tables are turned and it may be said that physics has cut the 

 atoms chemistry was content to leave undivided." 



It has cut them by showing that the corpuscle is a con- 

 stituent of the atom carrying a definite charge of negative 

 electricity, and, since with any charge of electricity an equal 

 charge of the opposite kind is always associated, it is to be 

 expected that negative charge on the corpuscle is associated 

 with an equal charge of positive electricity. Then the pri- 

 mordial system would be an electrical doublet, with a negative 

 corpuscle at one end and an equal positive charge at the other, 

 the two ends being connected by lines of electric force which 

 are supposed to have a material existence. The positive elec- 

 tricity is supposed to be spread over a very much larger sur- 

 face than the volume of the corpuscle. The lines of force 

 will be more condensed near the corpuscle than at any other 

 part of the system, and therefore the quantity of ether bound 

 by the lines of force, the mass of which is regarded as the 

 mass of the system, will be very much greater near the cor- 



