174 THE NEW KNOWLEDGE. 



(a thimbleful) of this emanation in the form of a gas we 

 should find that it possessed the power oi emitting, alto- 

 gether, over seven million calories of heat ! This is more 

 than sufficient to raise 15,000 pounds of water one degree, 

 and all this heat from a thimbleful of an invisible gas ! 

 The important phase of this statement is that it is alto- 

 gether outside of any hypothesis or theory. It is a simple 

 straightforward fact. Now, the heat evolved by explod- 

 ing the same volume of hydrogen and oxygen mixed in the 

 proportions required to form water is about two calories. 

 We find then that the heat evolved by the radium emanation 

 is over three million five hundred thousand times greater than 

 that let loose by any known chemical reaction. This seems to 

 be an unanswerable reply to those who would ascribe the 

 energy of radio-activity to ordinary chemical action or, on 

 the other hand, to those who would ascribe it, instead, to 

 an external source which, hypothetically, the radium atom 

 alone has the power to respond to. With the passing 

 away of these interpretations we are locked up with the 

 only other conclusion possible, that the radio-activity is 

 due to an enormous store of energy within the radium atom 

 itself. The energy of radio-activity is intra-atomic. 



The amount of heat generated by radium gives us some 

 additional general information. In any mass of radium 

 not all its atoms are disintegrating at the same time. In 

 the foregoing chapter we were led to understand that they 

 would go to pieces only as they became unstable, and that 

 this instability was a mere chance for an individual atom, 

 though a constant for the average one. It is interesting 

 to know how many atoms of radium disintegrate per 

 second. If we ascribe the heat emission to the alpha par- 

 ticles we are let into the secret. In the case of radium 

 there are at least four stages in the disintegration, each 



