54 THE ADVANCE OF SCIENCE 



heat when they are dissociated, and a 

 host of other molecular phenomena, have 

 been shown to be deducible from the dy- 

 namical and statical principles which ap- 

 ply to molar motion and rest ; and the 

 tendency of physico-chemical science is 

 clearly towards the reduction of the prob- 

 lems of the world of the infinitely little, 

 as it already has reduced those of the in- 

 finitely great world, to questions of me- 

 chanics.* 



In the meanwhile, the primitive atomic 

 theory, which has served as the scaffold- 

 ing for the edifice of modern physics and 

 chemistry, has been quietly dismissed. I 

 cannot discover that any contemporary 

 physicist or chemist believes in the real 

 indivisibility of atoms, or in an inter- 

 atomic matterless vacuum. ' Atoms ' ap- 



* In the preface to his Mecanique Chimique M. 

 Berthelot declares his object to be ' ramener la chimie 

 tout entiere . . . aux memes principes mecaniques qui 

 regissent deja les diverses branches de la physique.' 



