364 THE CHEMICAL PROBLEMS OF TO-DAY. 



limits wliicli to this day sire imposed upon physics in regard to the law 

 of jiiavitalion ), must answer these questions : What is Chemical Affinity f 

 and What is Valency f 



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

 solution of these enij^nias; but he who ()ursues chemical methods, who 

 stands iu the midst of chemical work — which aims only, as at a far 

 distant task, at the discovery of a sure |>a</i — still sees such obstacles 

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

 chemical era, lie tinds 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 — withiti the appointed limits — the most 

 importaut achievements of chemistry, we can not, 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 academical occui)ation. 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 speak 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 ai)pliances 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 in 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 i)ursued with astonishing success the investigation 

 which has made spectral analysis the most potent of scientific weai)ous, 

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

 the older minds and kindling iu the minds of mere school boys thefiame 

 of enthusiasm in the study ami 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 tlien> today in (b'tail would be but carrying owls to AiImmis. 

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

 younger one of them — whose scientilic fertility was only etpialled by 

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



