8 president's address. 



ventured on remarks as to their personal qualities, it is because it may 

 be said of all of them that they fought a good fight and maintained 

 the faith that only by patient and unceasing scientific work is human 

 progress to be hoped for. 



It has been the usual custom of my predecessors in office either to 

 give a summary of the progress of science within the past year or to 

 attempt to present in intelligible language some aspect of the science 

 in which they have themselves been engaged. I possess no qualifica- 

 tions for the former course, and I therefore ask you to bear with me 

 while I devote some minutes to the consideration of ancient and modern 

 views regarding the chemical elements. To many in my audience part 

 of my story will prove an oft-told tale ; but I must ask those to excuse 

 me, in order that it may be in some wise complete. 



In the days of the early Greeks the word ' element ' was applied 

 rather to denote a property of matter than one of its constituents. 

 Thus, when a substance was said to contain fire, air, water, and earth 

 (of which terms a childish game doubtless once played by all of us is a 

 relic), it probably meant that they partook of the nature of the so-called 

 elements. Inflammability showed the presence of concealed fire; the 

 escape of ' airs ' when some substances are heated or when vegetable 

 or animal matter is distilled no doubt led to the idea that these airs 

 were imprisoned in the matters from which they escaped ; hardness and 

 permanence were ascribed to the presence of earth, while liquidity and 

 fusibility were properties conveyed by the presence of concealed water. 

 At a later date the ' Spagyrics ' added tbree ' hypostatical principles ' 

 to the quadrilateral; these were ' salt, ' sulphur,' and ' mercury.' The 

 first conveyed solubility, and fixedness in fire; the second, inflamma- 

 bility; and the third, the power which some substances manifest of 

 producing a liquid, generally termed ' phlegm,' on application of heat, 

 or of themselves being conveiled into the liquid state by fusion. 



It was Robert Boyle, in his ' Skeptical Chymist, ' who first contro- 

 verted these ancient and mediaeval notions, and who gave to the word 

 ' element ' the meaning that it now possesses — the constituent of a 

 compound. But in the middle of the seventeenth century chemistry 

 had not advanced far enough to make his definition useful ; for he was 

 unable to suggest any particular substance as elementary. And, indeed, 

 the main tenet of the doctrine of ' phlogiston, ' promulgated by Stahl 

 in the eighteenth century, and widely accepted, was that all bodies 

 capable of burning or of being converted into a ' calx,' or earthly 

 powder, did so in virtue of the escape of a subtle fluid from their pores ; 

 this fluid could be restored to the ' calces ' by heating them with other 

 substances rich in phlogiston, such as charcoal, oil, flour, and the 

 like. Stahl, however false his theory, had at least the merit of having 



