MATTER 76 



convincing proof that matter is merely a condition^ 

 the condition of positive and negative electrons 

 grouped in the manner and pattern of the elements. 

 For when the constituents of an atom are not in 

 the specific combination that spells the atom, they 

 are ultimate units (positive and negative electrons) 

 with properties of their own. 



Sometimes, rather loosely, electrons are referred 

 to as "material," because of the "mass" of the elec- 

 tron; though in view of the marked differences 

 between electrons and atoms it is desirable that the 

 terms "matter" and "mass" should not be employed 

 indiscriminately and as exact synonyms. "Mass" 

 is not held by physics to be a measure of extension, 

 or the quantity of matter, but — of electromagnetic 

 origin — a measure of the energy content of a body, 

 relative (changing with change of velocity), and 

 registering as resistance to change (acceleration) of 

 motion. (On the basis of the relativity principle of 

 Einstein, the mass of a body is considered equal to 

 its energy content divided by the square of the veloc- 

 ity of light. E. Madelung, P. P. Ewald, Max 

 Born.) 



It is an aid to clear thinking to reserve and 

 apply the term "matter" exclusively to the ninety- 

 two chemical elements, the atoms, and their com- 

 pounds. 



