SOUTHERN CALIFORNIA ACADEMY OF SCIENCES. 103 



RADIUM. 



[Extracts from an address before the University Club of Lcs Angeles, October 8, 19(13^ 

 by Wni. H. Knight, former 1 resident of the Southern California Academy of Sciences.] 



Eecent discoveries in the chemical and physical sciences have been 

 so rapid and so bewildering that the layman who has only time to- 

 glance at a fugitive paragraph here and there, gets but a hasty and 

 confused idea of the nature, significance and importance of these dis- 

 coveries. He reads of the occult X-ray darting through opaque sub- 

 stances, and after mastering a magazine article or listening to a scien- 

 tific paper on the subject, gets some adequate notion of the connection 

 between a Crookes tube, a high vacuum, an electric charge, a stream of 

 electrons from the cathode, a soft opalescent light, actinic rays projected 

 beyond the tube, and their power to render sensitive plates phosphor- 

 escent. 



His mind has hardly grasped the purport of these interesting facts 

 when Monsieur Becquerel, scion of a family of distinguished chemists, 

 informs him that uranium and other elements of high atomic weight,, 

 also possess the X-ray power, and because they possess this property 

 they are called radio-active substances. While physicists are busy in- 

 vestigating these mysterious phenomena and reconstructing their chem- 

 eal theories regarding atoms and the constitution of matter, two liither- 

 to unknown chemists, M. and Mme. Curie, focalize the attention of 

 the world itpon themselves by announcing the discovery of a new ele- 

 ment which seems to defy the laws of nature by giving forth light 

 and heat without perceptible loss of its substance or chemical change 

 of its particles. This is the wonderful radium. 



In order to prepare your minds for an adequate conception of the 

 infinitesimal fractions of matter and time with which our subject 

 compels us to deal, I present some statistics which, though startling, 

 are not more wonderful to contemplate than are the achievements of 

 the human mind, which, by tireless experiments and inexorable logic, 

 has reached these startling conclusions. They impress us with the- 

 truth that there is a sublimity in the infinitely minute of physics, not 

 less than in the infinitely vast of astronomical science. 



Lord Kelvin gives the number of molecules in a cubic centimetre 

 of air, measuring four-tenths of an inch each way, as twenty millions; 

 of millions of millions of oxygen and nitrogen particles. And yet, these 

 innumerable molecules occupy but a fraction of that space, about one- 

 sixteentli of a cubic inch, for they have plenty of room to be in con- 

 stant motion among themselves, the light shines through them without 

 appreciable obstruction, and if liquified by intense cold they will 

 form an insignificant globule in one corner of the enclosure. 



Each particle of air moves on an average, not more than one- 

 100,000th of a centimetre without hitting one of its fellows, and each 

 particle collides wath another particle no less than 5,000,000,000 times- 



