364 THE CHEMICAL PROBLEMS OF TO-DAY. 



limits which to this day are imposed upon physics in regard to the law 

 of gravitation), must answer these questions : What is Ghemieal Affinityf 

 and What is Valency? 



By means of laborious detail work, chemistry tries to approach the 

 solution of these enigmas; but he who pursues chemical methods, who 

 stands in the midst of cliemical work — which aims only, as at a far 

 distant task, at the discovery of a sure path — still sees such obstacles 

 to be cleared away that he gives up the hope of living to see the new 

 chemical era. He finds satisfaction in the consciousness of having ex- 

 erted his best abilities in the elucidation of some minor and precursory 

 principles. 



If now we begin to consider — within the appointed limits — the most 

 important achievements of chemistry, we cannot, at this place and at 

 this hour of our meeting, be in doubt as to what is to be mentioned iu 

 the first place. The hospitable city which shelters us boasts of an ad- 

 vantage which is envied her by every other alma mater; here, chemis- 

 try for more than a human lifetime has been represented by Robert 

 Bunsen, of glorious name, and the very days which find us here as- 

 sembled, follow immediately the moment in which this hero of science 

 has retired from his aciidemical occupation. Who does not think, at 

 such an hour, of the great teacher around whom ardent pupils from all 

 parts of the globe were accustomed to congregate ? But who, being 

 called upon to-day to si)eak of the results of chemistry within the 

 walls of Heidelberg, would not before all direct an eye upon that one 

 discovery which has lifted chemistry beyond terrestrial research, which 

 has enabled her, like astronomy, to search the universe and to dissect 

 the starry heavens, chemically, by the subtle appliances of analysis? 

 If "old Heidelberg'' has become a pearl amongst German cities by its 

 history, by its numerous traditions, by the incomparable beauty of its 

 situation, — if its university is the ideal of the German academical youth, 

 we may well regard as an immortal leaf iu its wreath of honor, along 

 with these glorious titles, the union of those two great men who first 

 met in this city in the most courageous enterprise of the penetrating 

 mind; who have pursued with astonishing success the investigation 

 which has made spectral analysis the most potent of scientific weapons, 

 and has rendered their names a charm calling forth the admiration of 

 the older minds and kindling in the minds of mere school boys the flame 

 of enthusiasm in the study and exploration of nature. The immeas- 

 urable results of that discovery — the consequences of which extend 

 every day over new territories — are known in the widest circles, and to 

 mention them to-day in detail would be but carrying owls to Athens. 

 It behooves us in this place to mention reverently the names of Bunsen 

 and Kirchhoff, to think of them with gratitude, and to hope that men, 

 their equals, may not be entirely wanting in the next generation! The 

 younger one of them — whose scientific fertility was only equalled by 

 his greatness of soul and the charming modesty of his heart — has 



