THE 

 LONDON, EDINBUROH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



SEPTEMBER 1884. 



XXII. On the Spectral Lines of the Metals developed by Explo- 

 dinrf Gases. By Gr. D. Liveing, M.A., F.R.S., Professor 

 of Chemistry, and James Dewar, M.A., P.R.S. } Jacksonian 

 Professor , in the University of Cambridge* '. 



"IVTOT long since Berthelot published the results of some 

 -i- 1 investigations, by means of a chronograph, of the rate 

 of propagation of the explosion of mixtures of oxygen with 

 hydrogen and other gases. He found that in a mixture of 

 oxygen and hydrogen in the proportions in which they occur 

 in water, the explosion progressed along a tube at the rate of 

 2841 metres per second ; not far from the velocity of mean 

 square for hydrogen particles, on the dynamic theory of gases, 

 at a temperature of 2000°. 



This is a velocity which, though very far short of the 

 velocity of light, bears a ratio to it which cannot be called 

 insensible. It is in fact about yo^ooo P ar ^' °* **■ ^ ence if 

 the explosion were advancing towards the eye, the waves of 

 light would proceed from a series of particles lit up in succes- 

 sion at this rate. This would be equivalent to a shortaning of 

 the wave-length of the light by about jo^qo o P ar ^ l an( ^ m 

 the case of the yellow sodium lines would produce a shift of 

 the lines towards the more refrangible side of the spectrum by 

 a distance of about T J T of the space between the two lines. It 

 would require an instrument of very high dispersive power and 



* Communicated bv the Authors. 

 Phil. May. S. 5. Yol. 18. No. 112. Sept. 1884. M 



