93 



of the upper shelf and regarded with new interest. In a day it had ceased 

 to be a forgotten, though curious, plaything, and had become a powerful 

 instrument of research. It was before Roentgen's discovery that a well- 

 known professor said to me that he considered it foolish for one to spend 

 any part of his departmental appropriation for a vacuum; that when he 

 paid out money he wanted something in return — not an empty space. And 

 yet this man was familial- with the work of Faraday and of Crookes, both 

 of whom with prophetic mind had foreseen and foretold. Let me cpiote 

 from a lecture by Faraday on the significant subject "Radiant Matter." 



1 "I may now notice a peculiar progression in physical properties (of 

 matter) accompanying changes of form, and which is perhaps sufficient to 

 induce, in the inventive and sanguine philosopher, a considerable degree 

 of belief in the association of the radiant form with the others in the 

 set of changes I have mentioned. 



"As we ascend from the solid to the fluid and gaseous states, physical 

 pi*operties diminish in number and variety, each state losing some of those 

 which belong to the preceding state. * * * The varieties of density, 

 hardness, opacity, color, elasticity and form, which render the number of 

 solids and fluids almost infinite, are now supplied by a few slight varia- 

 tions in weight and some unimportant shades of color. 



"To those, therefore, who admit the radiant form of matter, no difficulty 

 exists in the simplicity of the properties it possesses * * * . They point 

 out the greater exertions which nature makes at each step of the change 

 and think that, consistently, it ought to be greatest in the passage from 

 the gaseous to the radiant form." The lecture from which the foregoing 

 is a quotation was delivered in 1810, when Faraday was but twenty- four 

 years old. 



Let me quote again, this time from a lecture by Sir William Crookes 

 delivered sixty years later, more than thirty years ago, on the same sub- 

 ject — "Radiant Matter." 



"In studying this fourth state of matter we seem at length to have 

 within our grasp and obedient to our control the little indivisible particles 

 which with good warrant are supposed to constitute the physical basis of 

 the universe. We have seen that in some of its properties radiant matter 

 is as material as this table, whilst in other properties it almost assumes 

 the character of radiant energy. We have actually touched the borderland 

 where matter and force seem to merge into one another, the shadowy realm 

 'Life and Letters of Faraday, Vol. 1, p. 308. 



