io6 SOUTHERN CALHORNIA ACADEMY OE SCIENCES. 



active emanations, is their extreme delicacy. The spectroscope tells us 

 what elements are dancing in the flames of a star so distant that its 

 light only reaches the eye through the lens of a telescope, but J. J. 

 Thomson, in his Belfast address, speaking of the ions projected through 

 the glass walls of a Crookes tube and called X-rays, and of other 

 radio-active rays, felt warranted in making the statement that "radio- 

 activity is 5000 times as delicate as the spectroscope, it matters not 

 whether the arc, spark, absorption or phosphorescent spectrum be made 

 use of. ^^ 



"We have in the radium salts," says Dr. KaufPmann, an eminent 

 German physicist, ' ' a class of bodies which are in the position to throw 

 off electrons without any outside influence. We stand before a perfect 

 riddle as regards the source of energy, likewise of the whole mechan- 

 ism of this phenomenon, especially as it appears that here velocities 

 have to be treated which are nearly equal to that of light; velocities 

 which we can reach by meatus of electrical forces, in actual cathode rays, 

 only after overcoming enormous difficulties. Thick lead plates are radiated 

 through at this velocity without a noticeable loss of energy. But just 

 this behavior of the electrons at such tremendous velocities seems suited 

 to furnish explanations in connection with the deepest questions con- 

 cerning the constitution of the electrons, likewise of the atoms." 



Eadium emits ions that have a velocity of 120,000 to 130,000 miles 

 per second, and that penetrate solids and blister the flesh. What are ions? 

 Certain substances radiate into space myriads of particles far smaller 

 than the theoretical atom. Corpuscles, they are called by J. J .Thom- 

 son, and ions by other physicists. In the new theory of force, elec- 

 tricity, and matter, these ions take the place of ether vibrations in 

 fundamental physics. Sir Wm. Crookes suggests that the energy of 

 radium is supplied by collisions of air molecules with the radium atoms. 

 But the question still obtrudes itself, why are the ions of radium thrown 

 off? Air molecules collide with the atoms of other substances and no 

 such miraculous effect is promised. For the moment the world must 

 content itself by simply stating the facts attending the strange phe- 

 nomena. 



A writer in the Engineer says: "It may perhaps turn out that 

 radium is doing nothing more in one way than a magnet does in an- 

 other. They both develop energy, apparently without help. Why and 

 how remains to be explained. ' ' 



Crookes calls attention to some calculations of Johnstone Stoney, 

 showing that an enormous amount of energy is locked up in the molecular 

 motions of quiescent air, amounting to 140,000 foot-pounds in each cubic 

 yard of the atmosphere. He referred to the kinetic energy which 

 impels each molecvile to be incessantly bombarding its fellows or the 

 objects in its vicinity, which presses with a force of 15 pounds per 

 square inch upon all bodies at sea-level. Now Crookes conjectured 

 that radio-active bodies of high atomic weight might draw upon this 

 store of energy in some unknown or hitherto unexplained manner. 



Though Thompson found by mathematical calculation that there 

 are from 700 to 1000 ions or corpiiscles in an atom of hydrogen, and 

 from 100,000 to 150,000 in the atoms of highly radio-active substances, 

 it is not to be assvimed that these corpuscles occupy the entire bulk, 

 infinitely minute as it is, of the atom. 



On the contrary, these ions may be likened to 1000, or 100,000 

 particles of dust seen floating in the atmosphere of a small bird cage 

 into which the sunshine is streaming. But they are revolving, with 

 unthinkable velocity, about a common center, in what is called a vortex 



