APPENDIX I 



AN ATTEMPT TO APPLY TO CHEMISTRY ONE OF THE 

 PRINCIPLES OF NEWTON'S NATURAL PHILOSOPHY 



BY PKOFESSOB MENDELEEFF 



A LECTURE DELIVERED AT THE ROYAL INSTITUTION OF GREAT BRITAIN 

 ON FRIDAY, MAY 31, 1889 



NATURE, inert to the eyes of the ancients, has been revealed to us as full of 

 life and activity. The conviction that motion pervaded all things, which was 

 first realised with respect to the stellar universe, has now extended to the 

 unseen world of atoms. No sooner had the human understanding denied to 

 the earth a fixed position and launched it along its path in space, than it was 

 sought to fix immovably the sun and the stars. But astronomy has demon- 

 strated that the sun moves with unswerving regularity through the star- set 

 tiniverse at the rate of about 50 kilometres per second. Among the so-called 

 iixed stars are now discerned manifold changes and various orders of move- 1 

 ment. Light, heat, electricity like sound--have been proved to be modes 

 of motion; to the realisation of this fact modern science is indebted for 

 powers which have been used with such brilliant success, and which have been 

 expounded so clearly at this lecture table by Faraday and by his successors, 

 As, in the imagination of Dante, the invisible air became peopled with spiritual 

 beings, so before the eyes of earnest investigators, and especially before those 

 of Clerk Maxwell, the invisible mass of gases became peopled with particles : 

 their rapid movements, their collisions, and impacts became so manifest that 

 it seemed almost possible to count the impacts and determine many of 

 'the peculiarities or laws of their collisions. The fact of the existence of 

 these invisible motions may at once be made apparent by demonstrating the 

 difference in the rate of diffusion through porous bodies of the light and 

 rapidly moving atoms of hydrogen and the heavier and more sluggish par- 

 ticles of air. Within the masses of liquid and of solid bodies we have been 

 forced to acknowledge the existence of persistent though limited motion of 

 their ultimate particles, for otherwise it would be impossible to explain, for 

 example, the celebrated experiments of Graham on diffusion through liquid 

 and colloidal substances. If there were, in our times, no belief in the 



