WHAT IS AN ELEMENT ? 149 



four and of these ten are gases, two are liquids, eight 

 elements are usually classed as non-inetals, since they do 

 not possess the lustre and some of the other properties of 

 rnetals ; and the remainder are metals. These substances 

 are classified as elements solely because no attempts to 

 convert one into another have up till now been successful ; 

 not because such change is in the nature of things im- 

 possible. But inasmuch as the properties of these 

 elements, and the changes which they undergo on 

 being brought together with other elements or compounds, 

 have been the subject of an enormous number of experi- 

 ments, and because no hint of transmutation has been 

 found, the conclusion as regards the immutability of 

 elements has been arrived at. Hence the ' transmutation 

 of elements ' has generally been regarded as impossible, 

 and as unattainable as perpetual motion, or as the ' quad- 

 rature of the circle.' 



Speculation, however, has a deep fascination for many 

 minds ; and it has been often held that it is not im- 

 possible that all elements may consist of a primal 

 substance 'protyle,' as it has been called in different 

 states of condensation. It will be worth while to spend 

 a few minutes in considering the reasons for this 

 opinion. 



About the beginning of last century, John Dalton 

 revived the old Greek hypothesis that all matter, elements 

 included, consists of atoms or minute invisible particles ; 

 these, of course, like the matter which is formed of them, 

 possess weight. Although they are so minute that any 

 attempt to determine their individual weight would be 

 out of the question, Dalton conceived the idea that at 

 least their relative weights could be determined, by ascer- 

 taining the proportions by weight in which they are pre- 

 sent in their compounds. The compound of hydrogen 

 and chlorine, for example, commonly known as muriatic 



