THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



JANUARY 1877. 



I. Contributions to the Theory of Luminous Flames, 

 By Dr. Karl Heumann*. 



UNTIL lately Davy's theory of luminous names sufficed to 

 explain all observed phenomena ; but recently our 

 knowledge has been enriched by a series of observations which 

 cannot be well brought into accordance with generally ac- 

 cepted notions. 



For example, the observation of Frankland that the flames 

 of hydrogen and carbon monoxide become luminous when 

 these gases are burned under pressure, is opposed to the 

 former view that the luminosity of flame is caused by 

 the presence of solid particles which become intensely 

 heated. Knapp's experiment, showing that the luminosity of 

 a flame may be diminished, not only by admitting air, but 

 also by a due admixture of nitrogen or carbon dioxide, can- 

 not be explained on the supposition of an oxidation of the 

 carbon previously suspended in the burning gas. For these 

 and other reasons, Davy's theory must either be altered or 

 replaced by a new hypothesis. The latter course does not 

 appear to me to be required. In the following contributions 

 I shall endeavour rather to develop this theory than to over- 

 throw it. The genius of Davy is made apparent when we 

 find that the discovery of so many facts since his day has in 

 no way overthrown his theory, but has only rendered a de- 

 velopment of it necessary in order to bring it into keeping 

 with an advancing science. 



* From Liebig's Ann. der Chemie, vol. clxxxi. part 2, pp. 129-153, and 

 vol. clxxxii. pp. 1-29. Translated by M. M. Pattison Muir, the Owens 

 College, Manchester. 



Phil. Mag. S. 5. Vol. 3. No. 15. Jan. 1877. B 



