590 CHARLES R. VAN HISE 



matter and ether; and chemistry considers mainly the actions and 

 transformations of matter through energy. But since energy is mani- 

 fest to the senses only through matter, and since matter does not 

 exist without manifestations of energy, the relations of the two 

 sciences are very intimate. In any book upon either subject the 

 treatment constantly passes over to the other; indeed, energy and 

 matter are inseparable — one cannot be considered without the other. 

 Recently the relations between physics and chemistry have become 

 even closer by the rise of the intermediate science, physical chem- 

 istry. This science completely bridges the gap between the two and 

 unites them as a whole into the conjoint science of physics-chemistry, 

 which is the science of energy and substance. As thus defined, 

 physics- chemistry becomes a synonym of natural philosophy in its 

 broad sense. 



While physics and chemistry are really a single science, it is to 

 be repeated that the chief point of view of physics proper is that 

 of energy, and the chief point of view of chemistry proper is that 

 of matter. This will be appreciated if one but mention the subjects 

 considered in text-books of physics and chemistry. Some of the sub- 

 jects of physics are sound, heat, light, and electricity. These are 

 all forms of energy. The chief subjects for consideration by chem- 

 istry are the elements and their combinations, such as helium, chlorine, 

 iron, calcium carbonate, etc. These are all forms of matter. Since 

 physics-chemistry treats of all the energy and substance within the 

 reach of our senses, physics and chemistry are the two sciences the 

 principles of which are believed to be applicable to the entire visible 

 universe. 



Astronomy treats of energy and substance in the heavens. It is 

 concerned primarily with the nature and development of the heavenly 

 systems. Under the above definition, astronomy is the science of 

 the physics and chemistry of the. heavens. Biology treats of energy 

 and substance in living organisms. Under this definition, biology 

 is the science of the physics and chemistry of organisms. Geology 

 treats of the energy and substance of the earth. Under this defini- 

 tion, geology is the science of the physics and chemistry of the earth. 

 It includes mineralogy. These definitions may not be complete, but 

 at least they are true so far as they go. 



