OPTICS, CHEMISTRY, AND BIOLOGY 63 



tion, a suitable temperature, and powerful electric 

 forces, we only require differences of elementary 

 substance in order to have what we call chemical 

 action. 



Differences of substance imply, as we know, differ- 

 ences of atomic weight. Taking the atomic weight 

 as the sole criterion of elementary substance, we 

 find less than a hundred elementary substances in 

 our world. There is at present no evidence that the 

 stars are graduated in a definite series of increasing 

 weights. If they were, and we could determine 

 their weights, we might, putting stars for atoms, 

 make out how many "substances" constitute the 

 supra-world. If there is an infinite gradation of 

 weights, and no corresponding planetary or elec- 

 trical difference between the various stars, we 

 must conclude that there is no " supra-chemistry." 

 In our present ignorance on this point, wo cannot 

 judge by analogy as to the substances, consisting of 

 infra-atoms, which constitute the infra-world. But 

 if there is a much greater specialisation of matter 

 in our world than in the supra-world, we may take 

 it that the chemical substances of the infra-world 

 are better defined than ours, and fewer in number, 

 with larger gaps between successive atomic weights. 

 would give the infra-atoms that greater stability 

 h would be necessary to resist tho further in- 

 crease of electric disintegrating force and the greater 

 energy of chemical reaction. 



