12 REPORT — 1895. 



had puzzled geographers from the days of Herodotus ; and the efforts 

 of Livingstone and Stanley and others have opened out to us the interior 

 of Africa. I cannot refrain here from expressing the deep regret which 

 geologists and geographers, and indeed all who are interested in the pro- 

 gress of discovery, feel at the recent death of Joseph Thomson. His 

 extensive, accurate, and trustworthy observations added much to our 

 knowledge of Africa, and by his premature death we have lost one of 

 its most competent explorers. 



Chemical, Astkonomical and Physical Science. 

 Chemistry. 



The report made to the Association on the state of the chemical 

 sciences in 1832, says that the efforts of investigators were then being 

 •directed to determining with accuracy the true nature of the substances 

 which compose the various products of the organic and inorganic king- 

 doms, and the exact ratios by weiglit which the different constituents of 

 these substances bear to each other. 



But since that day the science of chemistry has far extended its 

 boundaries. The barrier has vanished which was supposed to separate 

 the products of living organisms from the substances of which minerals 

 consist, or which could be formed in the laboratory. The number of dis- 

 tinct carbon compounds obtainable from organisms has greatly increased ; 

 but it is small when compared with the number of such compounds which 

 have been artificially formed. The methods of analysis have been per- 

 fected. The physical, and especially the optical, properties of the various 

 forms of matter have been closeh' studied, and many fruitful generalisa- 

 tions have been made. The form in which these generalisations would 

 now be stated may probably change, some, perhaps, by the overthrow or 

 disuse of an ingenious guess at Nature's workings, but more by that 

 change which is the ordinary growth of science — namely, inclusion in 

 some simpler and more general view. 



In these advances the chemist has called the spectroscope to his aid. 

 Indeed, the existence of the British Association has been practically coter- 

 minous with the comparatively newly developed science of spectrum 

 analysis, for though Newton,' Wollaston, Fraunhofer, and Fox Talbot 

 had worked at the subject long ago, it was not till Kirchhoff and 

 Bunsen set a seal on the prior labours of Stokes, Angstrom, and Balfour 

 Stewart that the spectra of terrestrial elements have been mapped out and 

 grouped ; that by its help new elements have been discovered, and that 

 the idea has been suggested that the various orders of spectra of the same 



' Joannes Marcus Marci, of Kroniand in Bohemia, was the only predecessor of 

 Newton who had any knowledge of the formation of a spectrum by a prism. He not 

 only observed that the coloured rays diverged as they left the prism, but that a 

 coloured ray did not change in colour after transmission through a prism. Plis book, 

 Thaumantias, liber do arcucailestl deque colornm apparentmrn natura, Prag, 16i8, was, 

 however, not known to Newton, and had no influence upon future discoveries. 



