6 INAUGURAL ADDRESS. 



venture to say, which is governed by so strict an ethical code- 

 none which does more at the same time for man's mental elevation 

 and for his proper humiliation. 



I propose to say something of the advancement of Chemical 

 Science (which is the only branch I am at all competent to deal 

 with) during the lifetime of this Association. I shall not attempt 

 anything like a complete or detailed account, which would be out 

 of place and indeed impossible. My object is rather to illustrate 

 the nature of the scientific quest and to indicate some of its main 

 lines at the present time. 



Let me first remind you that during the 19th century chemists 

 learned to think in molecules and atoms. To them, matter of any 

 sort is a collection of molecules, similar or dissimilar, constantly 

 moving in space with more or less freedom, crowded and mutually 

 hampered when aggregated as solid or liquid, relatively free but 

 occasionally colliding when scattered as gas. And each such mole- 

 cule is itself a more or less complex system of smaller parts — the 

 so-called atoms — atoms which are similar in the molecule of an 

 element but dissimilar in that of any one of the infinite variety of 

 compound substances. And these atoms, too, are moving within 

 the molecule, but are still held together by their mutual attractions, 

 while the molecular system moves as a whole through space. 

 These intra-molecular atomic motions are not inconsistent with 

 the maintenance of a definite and orderly arrangement, which gives 

 to the molecule a characteristic structure or architecture, and this 

 structure distinguishes one kind of molecule essentially from other 

 kinds, and indeed is the cause of many of the properties which we 

 recognise in that multitudinous collection of the molecules which 

 we call a sample of the substance. Somewhat similarly, the solar 

 system, moving in space, is distinguished from other heavenly 

 systems by the individuality of the sun and planets which compose 

 it and which, despite their important movements within the system, 

 hold together and give to it a structure or configuration that is 

 peculiarly its own. Nor is the molecule less real to the chemist 

 than is the solar system to the astronomer. True, it is so minute 

 that he never sees it, and all his knowledge of it is merely the result 

 of logical inference from actually observed phenomena. But is 

 there so much difference after all ? Does anyone really see the 

 solar system ? Are the larger and smaller spots of light that we 

 see in the sky (with or without the telescope) a really self-evident 

 revelation of the complicated story told us by astronomers ? Is 

 not this also a triumphant illustration of the power of mind to argue 



