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By J. Norman Collie, Ph.D., F.R.S., 

 Professor of Chemistry to the Pharmaceutical Society. 



IN the early days air was looked upon as an elementary sub- 

 stance, and for many hundreds of years it was considered one 

 of the four elements — earth, air, fire, and water being the 

 four. These elements were not looked upon quite in the same 

 light as we look upon elements nowadays. They had more to do 

 with the properties of substances in general, and not with actual 

 elementary substances, and it was not till about two hundred years 

 ago that definite ideas began to be collected on the subject of air, 

 and it was due to an English chemist — I think many of the great 

 discoveries in chemistry have been due to English chemists — that 

 our ideas on the subject of air first began to take a definite form. 

 It was towards the end of the seventeenth century — over two hun- 

 dred years ago — that Robert Boyle, an Englishman, first of all 

 published a work on the air, and the various subjects which related 

 to the air. I have a slide here which I should like to show you of 

 a portrait of Robert Boyle himself. I should like to show you 

 the portraits of several of those chemists who worked on air, and 

 who brought the knowledge that we possess of air up to the 

 beginning of this century. Robert Boyle, the first I will mention, 

 was a chemist who investigated not only air, but a great many 

 other substances besides, but he was particularly interested in air 

 and its various properties. He had rather vague notions, how- 

 ever, on the subject of air, but he was one of the first chemists 

 who combated the old idea of earth, air, fire, and water being ele- 

 ments, and he specially points out that there is no reason why we 

 should in any way limit the number of elementary substances to 

 four, and no reason why air should be an elementary substance ; 

 in fact, he seemed to think there were a great many different kinds 

 of air, as they were called in those days — " gas " being a much 

 later term, and that the different kinds of "gases" he investigated 



* Lecture delivered before the Pharmaceutical Society. F'rom the Phar- 

 maceutical Journal. 



