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mony of the very high value which the Society attaches to your 

 researches. It is our earnest hope that your health will be such 

 as to permit you, in addition to your important public duties, to 

 continue your most valuable scientific labours. 



The Council have awarded the Rumford Medal to Professor 

 Kirchhoff, of Heidelberg, for his researches on the Fixed Lines of 

 the Solar Spectrum, and on the Inversion of the Bright Lines in the 

 Spectra of Artificial Light. 



The existence of definite rays in the light of flames coloured by 

 various salts has long been known, and attracted the attention of Sir 

 John Herschel as long ago as 1822 ; and in papers published a few 

 years later, Mr. Fox Talbot called attention to the value and deli- 

 cacy of this character in qualitative chemical analysis ; showing, for 

 example, how the red produced by lithia, and that produced by 

 strontia, might thus be instantly distinguished by the difference in 

 the system of bright lines seen in their respective spectra. He re- 

 marked at the same time what an exceedingly minute quantity of a 

 metallic substance could thus be detected in a flame. But chemists 

 generally were not aware of the precious means of qualitative analysis 

 thus lying at their command ; and, in fact, the elaboration of this 

 mode of qualitative chemical analysis required a combination of 

 chemical and physical observations for which the same individual 

 was seldom properly qualified and equipped. It was necessary, on 

 the one hand, to prepare a variety of substances in the highest state 

 of chemical purity, and, on the other, to take a number of careful 

 angular measures of the positions of bright lines in the spectra of 

 various flames. 



This labour has now been in great measure accomplished by the 

 joint exertions of Professors Kirchhoff and Bunsen, to whom indeed 

 is due the merit of having made this mode of chemical research 

 available to the scientific world, and of having caused spectroscopes 

 to be now in the hands of chemists generally, by whom they are 

 employed with the greatest advantage in the qualitative examination 

 of inorganic substances. Already the method has led to the discovery 

 of three new elements, Caesium and Rubidium in the hands of 

 Professor Bunsen, Thallium in those of our own countryman, 

 Mr. Crookes. 



