lvi. ABSTRACT OF PROCEEDINGS. 
physical properties of the elements which enabled the 
atomic weights to be verified with considerable accuracy. 
It was soon found that a very profound and highly significant 
relationship existed between the atomic weights of the 
elements and their general properties. This was first 
observed by Newlands the English chemist, but developed 
later by Mendeleef into the Periodic law. This highly 
important generalization, based as it is on the Atomic 
Theory, is one of the most important achievements of this 
theory. In other directions the Atomic Theory has 
developed in ways equally important and unforeseen. By 
its means chemists have been able to learn something of 
the constitution of the most complex forms of matter. The 
doctrine of valency introduced by Frankland is a direct 
corollary of the atomic theory. The modern development 
of the theory of valency has led us to the most ingenious 
and beautiful explanations of the internal groupings of the 
atoms in chemical substances, and has been especially pro- 
lific in the discovery and synthesis of new substances in 
the Benzene group, notably the dyes and other remarkable 
substances known as the coal tar derivatives. It has also 
served to explain the remarkable optical behaviour of 
substances otherwise identical. At the present time we 
are undergoing a change in our conception of the nature of 
the atom. Research into the electrolysis of solutions, the 
ionization of gases and radio-activity have familiarized 
us with the idea that the atom is not to be regarded as 
indivisible, but as composed of yet smaller particles—elec- 
trons—the escape of which from the atom give rise to the 
phenomena of radio-activity. All these manifestations can 
only be satisfactorily explained on the assumption that 
what we observe is the disintegration of the atom, and that 
the energy is derived from the internal energy,a view which 
brings us to the new conception that the atomic weight isa 
