CHAPTER VII 

 THE MOLECULAR COMPOSITION OF MATTER 



THAT the realities with which science deals are matter 

 and energy was not appreciated until comparatively 

 recently. In 1777 the indestructibility of matter was 

 established by experiments of Lavoisier, a French 

 chemist. In 1843 experiments of Joule established the 

 indestructibility of energy. The experiments of the 

 former will be considered in this chapter, and those 

 of the latter in a later chapter. It is upon the basis 

 of the indestructibility of these entities, energy and 

 matter, that we are entitled to consider them the 

 realities of science. 



A body of any kind of matter may be divided into 

 very fine particles, as we all know, just as a lump of 

 stone may be crushed under water until its particles 

 float away undiscernible to the human eye. Pulveriz- 

 ing stone gives merely small particles of stone and does 

 not produce any change except of size. The particles 

 of water vapor in the air about us are even smaller than 

 anything which can be seen with the best microscope, 

 but still they are unaltered in kind. In the past it 

 has sometimes been argued that there was no limit 

 to such divisibility of matter, that matter in fact was 

 " infinitely divisible." On the other hand, there were 

 philosophers like Democritus (420 B.C.) who held that 

 it is granular in its composition, consisting of small 



70 



