ORGANIZATION OF THE SCIENCES 



account ; but we cannot study living organisms 

 without appealing to physics and chemistry at 

 every step. 



In the science of inorganic phenomena a 

 somewhat less obvious principle of division 

 next presents itself. Inorganic physics may be 

 divided into celestial and terrestrial physics ; of 

 which the first treats only of gravitative force as 

 manifested in the relatively simple phenomena 

 of the mutual attractions of the heavenly bodies; 

 while the second treats not only of gravitative 

 force as manifested throughout relatively com- 

 plex terrestrial phenomena, but also of the mo- 

 lecular forces, cohesion and chemism, and of 

 the modes of undulatory motion called sound, 

 heat, light, magnetism, and electricity. This 

 second division may be again subdivided into 

 physics proper and chemistry. The first treats 

 of those changes in which the relative positions 

 of the molecules of matter are altered homo- 

 geneously, resulting in increase or decrease of 

 volume, or other change of physical state; 

 while the second treats of those changes in 

 which the relative positions of molecules are 

 altered heterogeneously, resulting in the pro- 

 duction of new compounds and new affinities. 

 Of these two sciences, manifestly physics should 

 be first studied. We can to a certain extent 

 generalize th5 laws of reflection and refraction, 

 condensation and rarefaction, without help from 



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