SECTION B.— CHEMISTRY. 



THE RELATION OF ORGANIC 

 CHEMISTRY TO BIOLOGY 



ADDRESS BY 



PROFESSOR GE0RC4E BARGER, M.A., D.Sc, F.R.S., 



PRESIDENT OF THE SECTION. 



Since the British Association fii'st met in South Africa, Afrikaans has 

 become an ofHcial language, and I will therefore take as my point of 

 departure the Dutch word for chemistry, still commonly used in Holland : 

 Scheikunde, the science of separating. The German analogue, ' Scheide- 

 kunst,' hardly applies to chemistry as a whole, and is now mainly restricted 

 to the separation of gold and silver — ' parting,' as we say. Since the 

 purification of a substance is merely the separation of impurities, and 

 since purification constitutes no small part of the labours of the chemist, 

 whether he be an inorganic, an organic, or a biochemist, it will be seen 

 that the Dutch term is really apt ; it is, moreover, an accurate description 

 of chemical analysis ; perhaps it will appeal least to those physical 

 chemists who are content to leave the purification of their materials to 

 the manufacturer. Since, in the last resort, we are dependent on 

 naturally occurring materials, which hardly ever occur in a state of 

 purity, it follows that the early chemists were even more concerned with 

 separating one substance from another than many of us are to-day. 

 Progress was at first limited to mineral substances capable of withstanding 

 powerful reagents and a high temperature ; much of the old chemistry is 

 concerned with the heavy metals. The substances formed in such large 

 numbers by living beings are much less stable, and their isolation demands 

 a special technique. It is significant that, in spite of their knowledge of 

 the smelting of ores, of the manufacture of glass, and of many other arts, 

 the ancients failed to distil alcohol. Later, the chemical investigation of 

 organic material was apt to consist in destructive distillation, naturally 

 adding little to knowledge. Only the more volatile and stable substances 

 could be isolated in this fashion. Thus, in 1770, four acids were known, 

 formic and acetic, obtained by distillation, succinic and benzoic, obtained 

 by sublimation. Oxalates and tartrates were known, but not the free 

 acids. By distilling alcohol with strong acids, ether, ethyl nitrate, and 

 ethyl chloride had been obtained.^ The wet method of separation, by 

 crystallisation from solution, had scarcely been applied to organic 

 substances. Nevertheless Marggraf »f Berlin had isolated beet sugar in 

 1747 ; this chemist was also the first to purify glucose. 



* I have taken these and some other details from Graebe's Geschichte der 

 organischen Chemie. 



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