92 THE WORLD-ENERGY 



this in no way obscures the fact that each new compound 

 developed through change in quantitative relations ex- 

 hibits new qualitative characteristics. Take, for exam- 

 ple, the simplest cases those of allotropic substances. 

 Oxygen combines with itself, the result being what is 

 called ozone. The quantitative change is simply one 

 from extensive to intensive quantity. Externally the 

 only change is a reduction of one-third in volume. So, 

 too, carbon presents the three strikingly different states of 

 graphite, coal, and diamond, by mere variety in the com- 

 bination of carbon particles with carbon particles. 



The same remarkable development of qualitative dif- 

 ference through mere change in quantitative relation is seen 

 again in all those cases where one element combines with 

 another in more than one ratio. A conspicuous example 

 is found in the various oxides of nitrogen, where a con- 

 stant quantity (28 parts by weight) of nitrogen combines 

 successively with five different quantities (16, 32, 48, 64 

 and 80 parts by weight) of oxygen, producing as many 

 qualitatively different results. It is noticeable that each 

 succeeding quantity of oxygen in the series is a simple 

 multiple of the first. And chemists have often called 

 attention to the fact that no combinations take place be- 

 tween these elements in other proportions than those given. 

 It was precisely such facts as these that led Dalton to enter 

 upon those investigations which resulted in his revival of 

 the atomic theory under a genuinely scientific form. 



The core of Dalton's discovery is that this combination 

 in definite proportions is the universal characteristic of all 

 chemical activity that chemical compounds are, without 

 exception, dependent upon precisely fixed quantitative 

 relations. Nor is it without significance that in Dalton's 



