ADDRESS. 45 



of a natural alkaloid. A proximate synthesis of atropine, the alkaloid of 

 the deadly nightshade, has been accomplished by Ladenburg. It seems 

 further probable that at no distant date the useful alkaloids, such as 

 quinine, may also be synthesised, inasmuch as quinoline, one of the pro- 

 ducts of the decomposition of quinine and of some of the allied bases 

 has recently been prepared by Skraup by a method which admits of its 

 being obtained in any quantity. 



Much also has been done in the way of building up compounds the 

 existence of which was predicted by theory. Indeed the extent to which 

 hitherto undiscovered substances can be predicated is doubtless the 

 greatest triumph achieved by chemists during the past fifty years. 



As yet, however, only the statical side of chemistry has been de- 

 veloped. Whilst the physicist has been engaged in tracing, for the 

 gaseous condition at least, the paths of the molecules and calculatino- 

 their velocities, the chemist, whose business is with the atoms within 

 the molecule, can point to no such scientific conquests. All that he 

 knows concerning the intramolecular atoms, and all that he expresses 

 in his constitutional formulce is, the particular relation of union in which 

 each of these atoms stands to the others — Avhich of them are directly 

 united (as he expresses it) to other given atoms, and which of them are 

 in indirect union. Of the i-elative positions in space occupied by these 

 atoms, and of their modes of motion, he is absolutely ignorant. In like 

 manner in a chemical reaction the initial and final conditions of the 

 reacting substances are known, but the intermediate stages — the modes 

 of change — are for the most part unexplained. 



The feeling that no number, however great, of successfully solved 

 problems of constitutional chemistry (as at present understood), and 

 no number of syntheses, however brilliant, of natui-al compounds, could 

 raise chemistry above the statical stage — that the solution of the dyna- 

 mical problem cannot be arrived at by purely chemical means has led 



many chemists to approach the subject from the physical side. The 

 results which the physico-chemical methods, as exemplified in the laws 

 already alluded to of Dulong and Petit, Avogadro, and Mitscherlich, 

 have yielded in the past, offer the best guarantee of their success in 

 the future. And the advantages of many of the physical methods are 

 obvious. Every purely chemical examination — whether proximate or 

 ultimate — of a compound, presupposes the destruction of the substance 

 under examination : the chemist ' murders to dissect.' But observations 

 on the action of a substance on the rays of light, on the relative volumes 

 occupied by molecular quantities of a substance, on its velocity of trans- 

 piration in the liquid or gaseous state— these teach us the habits of 

 the living substance. The rays of light which have threaded their way 

 between the molecules of a body have undergone, in contact with these 

 molecules, various specific and measurable changes, the nature and 

 amount of which are assuredly conditioned by the mass, form, and other 

 properties of the molecules : the plane of polarisation has been caused to 



