DIVISIBILITY OP MATTER ATOMIC THEORY. 75 



indeed was already recognised, how much of future 

 knowledge, not merely as respects particular facts, but 

 general laws, is wrapped up in this molecular theory. 

 It is through the infinitely small that we may best 

 reach a comprehension of the architecture, organic and 

 inorganic, of the material world. 



Without discussing in detail the several bearings 

 of molecular philosophy, I may notice one cardinal 

 point important from its relation to others, viz., the 

 fact that in proportion as a compound is more complex 

 in its parts it becomes more unstable, more liable to 

 dissolution. All the most explosive compounds of 

 which we have knowledge come under this general 

 law. So, it may be though here we must speak more 

 doubtfully do those strange phenomena of ferments, 

 of animal and vegetable poisons, and of the specific 

 poisons of certain epidemic diseases. In the latter 

 class of facts we have the most striking proofs of the 

 infinite divisibility of matter, and of those wonderful 

 relations of its infinitesimal parts which, by a slight 

 change in their proportion only, can convert an inno- 

 cuous substance even an article of food into one 

 which becomes an instant cause of disease or death. 

 Physiology, as a part of general science, has much yet 

 to learn here, though it may probably never be able to 

 tell us in what physical changes that immunity con- 

 sists, which renders a person who has once had the 

 smallpox permanently insusceptible of infection from 

 the virus of this disease. 



La molecule est un groupe d'atomes, form ant la plus petite quantite d'un 

 corps simple ou compose qui puisse exister a 1'etat libre, entrer dans un 

 reaction, ou en sortir. 



