348 DIRECT PROPERTIES OF MOLECULES 123 



cojnpare it with the total heat-energy contained in the 

 Vapour. He found that the energy needed for the illumina- 

 tion is vanishingly small in comparison with the total 

 energy. An atom, therefore, must be a structure in which 

 pendulous movements can be produced by very small forces. 



124. Vortex Atoms, Pulsating and Electrical 

 Atoms 



The considerations of this final chapter have taught us 

 much, and perhaps more than was to be expected, about 

 things which seem to remain as a last object, at least for 

 the present, for the comprehension of the natural philo- 

 sopher, viz. about atoms and molecules. We have been 

 able to investigate their shape, measure their size, and 

 estimate their w r eight ; we have also learnt that these small 

 entities exert powerful forces on each other when they come 

 close together. But we have not yet learnt sufficient about 

 their state to be able to solve the puzzle which lies before 

 us in the wonderful property of indivisibility to which 

 atoms owe their name. Indeed, the property of indivisi- 

 bility seems far more unintelligible than ever, now that we 

 know that the size of atoms is not infinitely small, but is 

 measurable in finite terms. The molecules and atoms con- 

 cerned in the theory of gases, and more especially with 

 mathematical physics, are small bodies which are only one 

 or more thousand times smaller than the smallest magni- 

 tude microscopically visible. We shall scarcely be able to 

 conceive that such large bodies are really indivisible elemen- 

 tary atoms. 



We shall be so much the less inclined to this belief as 

 many different reasons can be brought forward for the con- 

 clusion that the small particles, named atoms by chemists 

 and physicists, are not monads. The most obvious reason 

 is afforded by the simple relations which show a regular 

 connection l between the atomic weights and other pro- 

 perties of the chemical elements conditioned by these 



1 Compare Lotbar Meyer, Die modernen Theorien dcr Chemie, section 9, 

 ' Das Wesen der chem. Atome.' 



