SCIENCE 



[N. S. Vol. LIV. No. 1383 



eject a projectile with a speed of more than 

 about a mile per second, you see how feeble 

 imitations of nature we have as yet been able 

 to produce. No band of Mexican bandits 

 running amuck on a Texas town can compare 

 for a moment with a colony of radium atoms 

 which perpetually bombard their neighbors 

 with broadsides having muzzle velocities of 

 12,000 miles per second. Not only that; these 

 atoms of radium have lighter ordnance also. 

 They shoot off in addition each second 71,000 

 billion particles that are one eight-thousandth 

 as heavy as these particles which I have called 

 the alpha particles, and which are essentially 

 helium atoms. If we call these alpha particles 

 the 13-inch guns of the radium atoms, then 

 we might say that they have also seventy-five 

 millimeter guns which shoot off relatively light 

 projectiles. These, however, have a speed 

 which is more than ten times as great as that 

 of the alpha particles. We call them beta 

 rays. They are simply free negative electrons, 

 endowed with a speed which is close to the 

 speed of light, namely, close to 186,000 miles 

 per second. But even that is not all. There 

 is still one other type of rays that are being 

 given off by this gram of radium. These other 

 rays are the wireless waves of the denizens of 

 the sub-microscopic world. They are ether 

 waves just like light or just like wireless 

 waves, except that the vibration frequency — 

 the number of oscillations per second which 

 the electronic inhabitants of the atom send 

 ofE — amounts to thirty billion billions per 

 second. These are the so-called gamma rays. 

 Now as to penetrating powers. The alpha 

 rays or helium atoms, shoot right through the 

 walls of a thin glass tube just as though there 

 were no wall there at all, and that, in itself, 

 has thrown new light on the structure of mat- 

 ter. It has shown us that the atom is itself an 

 existence which is mostly empty space. It 

 is like a miniature solar system through which 

 it is entirely possible for a new satellite or 

 planet to shoot without meeting anything. 

 One of these alpha particles shoots on through 

 hundreds of thousands of atoms before it is 

 brought to rest. It goes through seven centi- 

 meters of air which is of the order of a third 



of a foot. That is as far as the heavy projec- 

 tiles which are shot off from the radium atoms 

 can go. The lighter ordnance shoots a hun- 

 dred times as far and the gamma rays are a 

 hundred times more penetrating still. I have 

 thought you would be interested in actually 

 seeing for yourselves the effects of these rays. 

 I shall show first the effect of the gamma rays 

 because, being those that are used in thera- 

 peutics, they are the ones you are most likely to 

 be interested in. The gamma rays are simply 

 ether radiations of very short wave-length, and 

 whenever they pass through the atoms of mat- 

 ter they have the extraordinary power of 

 ejecting with great speed from these atoms the 

 electrons which are contained within them. 

 And when these electrons pass in turn 

 through other atoms they knock new electrons 

 out of these atoms and thus put many of 

 them into a condition in which they can make 

 new combinations more readily than when 

 they are not thus " ionized." Now there can 

 scarcely be any doubt that the therapeutic 

 effects of radium are simply due to the fact 

 that these ionized atoms have been put into 

 a condition to make new chemical unions, 

 i.e., to produce new substances which are de- 

 structive of the normal tissues as well as of 

 the cells of the disease which it is desired to 

 destroy. But in some instances, at least, the 

 disease is more susceptible than are the nor- 

 mal cells and consequently it becomes pos- 

 sible to arrest the growth of those disease cells. 

 As a matter of fact, so far as the therapeutic 

 effects of radium are concerned, the doctors 

 who are in charge of the radium institutes 

 will all tell you that you must not regard 

 radio-active treatment as a cure for cancer. 

 The only cure for cancer — the only certain 

 cure — is surgical. Nevertheless, the effects of 

 radium rays are to retard the growth of the 

 malignant tumors and therefore to prolong 

 life, so that, even in the case of cancers 

 which are not capable of being operated upon 

 — deep-seated concers — life can often be pro- 

 longed several years by radium treatment. 



The medical specialists will also tell you 

 that there are certain types of superficial tu- 

 mors and skin diseases which can be perma- 



