JOURNAL 



OF THE 



ELISHA MITCHELL SCIENTIFIC SOCIETY 



VOLUME XXX JANUARY. 1915 No. 3 



EECENT CONCEPTIONS OF THE ATOM 



BY F. P. VENABLE 



The original conception of the atom arose from the discus- 

 sion among the early Greek thinkers as to the indefinite divisi- 

 bility or ultimate indivisibility of matter. They were divided 

 into two schools of thought — the plenists and anti-plenists, 

 or vacuists. It was the belief of the latter school that all matter 

 was composed of indivisible particles or atoms, and vacua. 



These atoms are not mathematical points but are too small to 

 impress themselves upon the senses and are indivisible. They 

 differ in size, shape and weight; are in continuous motion (hence 

 the necessity for voids) ; and are endowed with some inclination 

 or force which causes them to meet in a selective way and by 

 their union form the various kinds of matter known to us. This 

 theory was the high achievement of pure reasoning with little 

 basis of experimental evidence. We accept the atoms but for the 

 vacua substitute the very original conception of Aristotle of a 

 quinia essentia or ether, of whose existence we still have no 

 tangible proof. 



Through the centuries this theory of atoms has come down 

 to us without important change or experimental support until 

 Dalton made use of it to explain the great underlying laws of 

 chemistry and attempted for the first time to determine the rela- 

 tive weights of these ultimate particles or atoms. 



Dalton's conception of the atom becomes of greater interest 

 in view of the modern speculations. In his New System of 

 Chemical Philosophy (p. 147) he writes: "A vessel full of any 



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