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J. MORISON : ADDRESS 



Let US begin witli the Elements. In ancient times, and indeed 

 up to comparatively recent days, it was usually asserted that 

 there were four elements or primordial substances of which all 

 things were composed, namely. Earth, Air, Water, and Fire. 

 We now know that these are not in any sense of the word 

 elementary. The first three may be looked upon as types of the 

 three different states or conditions of matter with which we are 

 familiar, while the fourth, Fire or Heat, is a form of energy. 

 Modern chemists acknowledge about 80 different elements, many 

 of them only discovered recently, and some of them of exceedingly 

 rare occurrence. The accepted definition of an element is : 

 " A substance which cannot be decomposed into simpler forms 

 of matter by any process at present known to us." These 

 elements combine with each other in various ways, and form 

 compound bodies, the properties of the compounds being often 

 quite dissimilar to those of their constituents. The elements 

 combine with each other in certain definite and unvarying 

 proportions. From these proportions, that is, the relative 

 quantities or masses with which they enter into combination, 

 what are called the atomic weights or combining powers of the 

 elements have been deduced. The Atomic Theory is that the 

 elements are built up of exceedingly minute bodies called 

 atoms, these atoms differing in weight and probalily in size 

 for each element according to its combining power ; that in 

 elementary bodies two or more atoms combine with each other 

 to form a molecule of the element which is the smallest quantity 

 of the substance which can exist in a free state ; and that two or 

 more atoms of different elements combine wdth each other to 

 foraa a molecule of a compound body. Thus two atoms of 

 hydrogen combine with one atom of oxygen to form a molecule 

 of water. The atoms vary in weight from hydrogen, which is 

 represented by 1, to radium, whose atom is counted as 224, and 

 uranium, the atomic weight of which is 238. 



So far the Atomic Theory may be considered as absolutely 

 proved. The word atom means indivisible, and it was believed 

 till very lately that atoms were really minute indestructible 

 particles of matter which could not be divided or altered in any 

 way. Recent experiments, however, with the new metal radium 

 and other elements of the same class have completely revo- 

 lutionized our ideas. These researches have clearly shown that 

 the atoms are not simple and indivisible, but are in reality 

 compound bodies made up of thousands of almost infinitely 

 minute particles which have been called corpuscles or electrons, 



