6 Dr. Beattv on 



sciences. The alchemist pressed forward on his quest, handing 

 down to his successors some grains of truth hidden under bushels 

 of error. The chemist dug deeper and built more securely. 

 Experimental Science was coming into its own. The time grew 

 ripe for an Atomic Theory which should co-ordinate and clarify 

 the masses of facts which had been discovered. 



In 1 80 1 Dalton produced his Atomic Theory. He shewed 

 that when chemical compounds are formed the weights of the 

 substances which combine bear simple numerical relations to each 

 other, and inferred that each element consists of small particles or 

 atoms, which combine with the atoms of other elements in simple 

 proportions. 



Dalton's views were, as was soon recognized, of enormous 

 value to the chemist. They allowed of simple mental images 

 being formed of the processes of chemical reactions, they explained 

 and classified previous results, and most important of all they 

 conferred the gifts of scientific prophecy on those who understood 

 them. 



Let us pass on to the great classification of the chemical 

 elements into groups which shewed strong family resemblances. 

 The recognition of such resemblances and their regular occurrence 

 as we pass from light to heavy atoms, which is known as Mendeleef's 

 Periodic Classification, led to strong suspicions that underlying the 

 atoms themselves was some more fundamental form of matter and 

 that one element differed from another merely in the geometric 

 distribution of these fundamental particles. 



Such speculations could only be verified by success in splitting 

 an atom to pieces and extracting from it its constituent parts. 



Tlie forces required to tear the atom asunder might be 

 expected to be very great, and indeed, we now know that very few 

 chemical reactions are capable of upsetting the equilibrium of 

 those extremely stable systems. Very violent collisions are required. 

 In order to impart great speed to an atom we must first electrify 

 it and allow strong electric forces to act on it : its speed will then 

 increase as long as it is subject to the electric forces. In order 

 that the atom may not lose speed by collisions or by the pull of 



