252 M. G. Kirchhoff on the History of Spectrum Analysis 



of red-fire and of the frequent occurrence of the yellow line, he 

 says, " The other lines may be attributed to the antimony, 

 strontia, &c. which enter into this composition. For instance, 

 the orange ray may be the effect of the strontia, since Mr. Her- 

 schel found in the flame of muriate of strontia a ray of that 

 colour. If this opinion should be correct, and applicable to the 

 other definite rays, a glance at the prismatic spectrum of a flame 

 may show it to contain substances which it would otherwise re- 

 quire a laborious chemical analysis to detect. " In a subsequent 

 communication*, the same physicist, after a striking description 

 of the spectra of lithium and strontium, continues — " Hence I 

 hesitate not to say that optical analysis can distinguish the 

 minutest portions of these two substances from each other with 

 as much certainty, if not more, than any other known method." 



In these expressions the idea of "chemical analysis by 

 spectrum-observations" is most clearly put forward. Other 

 statements, however, of the same observers, occurring in the 

 same memoirs from which the foregoing quotations are taken 

 (but not mentioned by Prof. Miller in his abstract), flatly con- 

 tradict the above conclusions, and place the foundations of this 

 mode of analysis on most uncertain ground. 



Herschel, in page 438 of his article on Light, almost imme- 

 diately before the words quoted above, says — " In certain cases 

 when the combustion is violent, as in the case of an oil-lamp 

 urged by a blowpipe (according to Fraunhofer), or in the upper 

 part of the flame of a spirit-lamp, or when sulphur is thrown 

 into a white-hot crucible, a very large quantity of a definite and 

 purely homogeneous yellow light is produced ; and in the latter 

 case forms nearly the whole of the light. Dr. Brewster has also 

 found the same yellow light to be produced when spirit of wine, 

 diluted with water and heated, is set on fire." 



Talbot states f — " Hence the yellow rays may indicate the 

 presence of soda, but they nevertheless frequently appear 

 where no soda can be supposed to be present." He then 

 mentions that the yellow light of burning sulphur, discovered 

 by Herschel, is identical with the light of the flame of a spirit- 

 lamp with a salted wick, and states that he was inclined to believe 

 that the yellow light which occurred when salt was strewed 

 upon a platinum foil placed in a flame " was owing to the water 

 of crystallization rather than to the soda; but then," he con- 

 tinues, " it is not easy to explain why the salts of potash, &c. 

 should not produce it likewise. Wood, ivory, paper, &c, when 

 placed in the gas-flame, give off, besides their bright flame, 



* Phil. Mag. 1834, vol. iv. p. 114. Chemical News, April 27, 1861. 

 f Brewster's Journal, v., 1826. 



