CHEMICAL ELEMENTS AND ATOMS — URBAIN 205 



tides must have neutralizing positive particles. The a particles of 

 radioactivity seem to reveal such elementary masses, but we are still 

 at a loss, for their mass is manifestly too great. 



Sir Ernest Rutherford, to whom we owe what is basic in our 

 actual ideas about atoms, noted that the a-radiation is the most 

 powerful form of energy at our disposal. This led him to con- 

 ceive the bombardment of the atomic structure with them. It is 

 useless here to go into the details of his experiments with which 

 you, my dear Brauner, are familiar. You know that by an irre- 

 futable interpretation of the observed facts in the case of nitrogen, 

 phosphorus, and several other elements, the atomic citadels had 

 been breached b}'^ these projectiles and that the splinters resulting 

 from the consequent explosions could be nought else but hydrogen 

 ions. In thus declaring war upon the stable atoms, Rutherford 

 formed a new branch of science showing artificial radioactivity, 

 one of the greatest discoveries of our extraordinary epoch. 



These experiments show that protons must be a constituent of 

 some atoms, but it does not follow that they are a universal con- 

 stituent of matter. But do you not think that at least provisionally 

 we may accord them this privilege? If you make this concession 

 we may mix with strict science a little pleasant philosophy: This 

 existence of tw^o chemical elements, the electron and the proton, out 

 of which everything in the ifniverse is made. 



As to the simplicity of its conceptions, modern science thus rivals 

 that of Aristotle. The ancients postulated four elements, we admit 

 only two. The atoms of Lucretius have become a little complicated 

 and those of Dalton have lost their primitive simplicity. Science 

 has gained in unity and has to a certain degree attained the ideal 

 which it has sought with varying fortune for 3,000 years. 



Yet, though the universe has been reduced thus to two constit- 

 uents, and the electrons and protons occur as the simplest reduc- 

 tion of our ideas, it does not follow that those ideas are perfectly 

 clear. Berzilius, subsequent to the beautiful experiment of Davy, 

 tried to explain matter through electricity and fabricated for the 

 purpose one of the most curious syntheses which the annals of 

 physical chemistry contains. I allude to his electrochemical theory 

 of which the classification will remain an eternal monument. He 

 knew nothing of the nature of electricity; for this he depended 

 upon the wisdom of future physicists. We physical chemists of 

 to-day do not tell what matter nor what electricity is. We merely 

 know them as phenomena. The least metaphysical among us see 

 in electrons and protons merely centers of convergence of lines of 

 force. That evidently explains nothing fundamental. It makes for 

 us a woi-ld formed of minute hairy points, the hairs strikingly 

 abstract, only indicating to us the possibility of some phenomena. 



