280 INTRA-ATOMIC ENERGY. 



The idea that radio-aetivity origuiate.s in a peculiar choinieal pnx-ess 

 has rallied to its .support .several einiiieut phy.sici.sts. Notably, it has 

 been adopted and defended by Rutherford. 



"Radio-activit}^" says he, ''is due to a succession of chemical 

 chanoes in which new types of radio-active matter are contiiuially 

 formed. It is a process of equilibrium in which the cost of the pro- 

 duction of new radio-activity is balanced l)y the loss of the radio- 

 activity already produced. The radio-activity is maintained by the 

 continual production of new quantities of matter possessing tempo- 

 rary I'adio-activity. 



"A radio-active body is, for that very reason, one which is being 

 transformed. Radio-activity is the expression of its inces.sant lo.ss. 

 Its change is necessarily an atomic disaggregation. The atoms which 

 have lost something are, l)y that fact alone, new atoms.""" 



Although the (juantity of energy radiated by the atoms that are 

 undergoing a commencement of disaggregation may be relatively 

 very great, the loss of material substance that occurs in these reac- 

 tions is very slight, precisely ])ecause of the enormous condensation 

 of energy that is contained in the atom. Profes.s<n- Becquerel has 

 estimated that 1 gram of radium loses 1 milligram of matter in a thou- 

 sand millions of years. Professor Curie contents himself with one 

 million j^ears. Still more modest, Professor Rutherford speaks only 

 of some thou.sands of j^ears, and Professor Crookes of hundreds of 

 3^ears. These ligures, the first of which are quite fantastic, are 

 reduced more and more as more accurate experiments are made. 



According to certain (experiments of my own,! gram would last 

 one hundred 3^ears, which is just the figure given by Professor Crookes. 

 The matter can only be absolutely settled by repeated experiments. 



Yet even if we accept the figure that Professor Rutherford gives of 

 some thousands of years for the duration of 1 gram of radium, it 

 would suflice to prove that if uranium, thorium, and radium had 

 existed with their radio-active properties in the geological epochs 

 they would long ago have disappeared. This again supports our theor}^ 

 that rapid spontaneous radio-activity appeared only after the bodies 

 became engaged in certain chemical combinations capal^le of afi'ecting 

 the stability of their atoms, combinations which we ma}' succeed in 

 reproducing. 



What is the nature of these combinations^ Of this we are yet 

 ignorant, l)ut the various examples cited in my preceding papers'' 

 prove that there exists a whole series of reactions (hydration of 

 various sulistances, decomposition of water, decomposition of carbide 

 of calcium, etc.), capable of causing atomic di.ssociation, and which 



« Philosophical Majjazine, February, 1903. 



?* Revue Scientifi(iue, April, 1900, i>. 892, and N<)veiul)er 15, 1902, j). (521. 



