Rollins — Cathode Stream and X- Light. 387 



only be necessary to exhaust the tube to the usual X-light 

 vacuum. The particles in the cathode stream from the radio- 

 active cathode would then meet with no more obstruction on 

 their way to the target to produce X-light, than would be 

 encountered by those of a cathode stream formed in the ordi- 

 nary, way. 



A distinguished American physicist has expressed the 

 opinion that the radio-active substances would be so intensified 

 as to act as substitutes for the complicated and troublesome 

 apparatus now required for producing X-light for medical pur- 

 poses. Having a high regard for his opinion I abandoned 

 experiments with X-light to work with these substances. 



Experiments showed that the light from them was different 

 in character from X-light, suffering diffusion in the tissues like 

 ordinary light to such an extent that the bones even of the 

 hand were not visible. The experiments indicated a differ- 

 ence, perhaps in velocity, between the units in the cathode 

 stream and those of the radio-active substances, because the 

 character of the two resulting radiations toward human tissues 

 was not the same when produced in the same vacuum. Experi- 

 ments of this nature require time and money. I was, there- 

 fore, disappointed with the results, for my interest in the 

 subjects mentioned in this paper was a desire to find the most 

 efficient radiation, to aid in the relief of human suffering. 



10. A cathode stream particle has a mass only 1/3000 of a 

 hydrogen atom. The particles are the ultimate units of which all 

 the elements are composed. That atoms are compound is prob- 

 ably true, though not yet proved by experiment. The theory 

 explains phenomena better than that of the indivisible atom. 

 That the particles in the cathode stream are the ultimate units 

 is absurd. 



I shall make a few suggestions in regard to each theory : 



On the theory of indivisible atoms, how shall we explain 

 differences in atomic weight, except by saying that such is the 

 nature of atoms? This is not a satisfactory answer to an 

 active mind. 



On the theory of a compound atom it may be explained by 

 saying that a light atom has fewer ultimate particles than a 

 heavy one, for as each particle must have the same weight 

 there would be more in a heavy atom than a light one, to 

 account for differences in atomic weights. 



That the particles in the cathode stream, however small, are 

 not the ultimate particles of which the universe is composed, is 

 shown by their having a familiar spectrum. If we could make 

 ultimate units give a spectrum, it would be a new one. In 

 this connection I mention a statement made in my notes 

 already referred to : 



