TfiE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE 



[FIFTH SERIES.] 



MARCH 1894. 



XXII. The Luminosity of Gases* 

 By Akthue Smithells, B.Sc* 



Part I. — The Luminosity of Flames free from Solid 



Particles j\ 



IN a brief note communicated to the Chemical Society in 

 1892 (Proc. Chem. Soc. no. 105) I described some 

 experiments on flame-coloration made with my flame-cone 

 separating apparatus, and in order to explain the results ob- 

 tained I adopted provisionally the view that flame-spectra in 

 some cases must be regarded as the direct effect of chemical 

 action. 



Almost simultaneously E. Pringsheim read before the Akad. 

 d. Wissenschaften, Berlin, a paper on " Kirchhoff's Law and 

 the Radiation of Gases," which was subsequently printed 

 in Wied. Ann. xlv. p. 428, 1892. In this paper Pringsheim 

 records an elaborate series of experiments on the radiation and 

 absorption of sodium vapour, and arrives at the conclusion 

 that the spectrum of sodium salts in a flame and of sodium 

 vapour heated in neutral gases is due directly to chemical 

 action. In a subsequent paper { Pringsheim has extended his 

 experiments to other substances and has obtained similar 

 results. 



* Communicated by the Author. 



f A summary of this part of the paper was read before the Chemical 

 Section at the Nottingham meeting of the British Association, Sept. 19, 

 1893 



\ Wied. Ann. xlix. p. 347 (1893). 



Phil. Mag. S. 5. Vol. 37. No. 226. March 1894. S 



