576 On the Spectrum of the Flame of Hydrogen. [June 17, 



error due to the cause poiuted out by the great French chemist, its 

 influence is in the present case inappreciable by existing means of 

 measurement, and no correction of the numbers obtained for the atomic 

 weight in question can be applied which shall have any real meaning. 



The other series (1 and 2) of experiments made to determine this 

 atomic weight do not involve the question of gaseous occlusion, at any 

 rate in the same form, as in them the metal itself was not used, b ut 

 certain of its compounds only. 



XIV. On the Spectrum of the Flame of Hydrogen." By 

 William Huggins, D.C.L., LL.D., F.R.S. Received June 

 16, 1880. 



Messrs. Liveing and Dewar state, in a paper read before the Royal 

 Society on June 10 {ante p. 494), that they have obtained a photograph 

 of the ultra-violet part of the spectrum of coal gas burning in oxygen, 

 and in a note dated June 8 they add that they have reason to believe 

 that this remarkable spectrum is not due to any carbon compound 

 but to water. 



Under these circumstances I think that it is desirable that I should 

 give an account of some experiments which I made on this subject 

 some months since without waiting until the investigation is more 

 complete. 



On December 27, 1879, 1 took a photograph of the flame of hydrogen 

 burning in air. As is well known, the flame of hydrogen possesses but 

 little luminosity, and shows no lines or bands in the visible part of the 

 spectrum, except that due to sodium as an impurity. 



Professor Stokes, in his paper " On the Change of Refrangibility of 

 Light,"* had stated that "the flame of hydrogen produces a very 

 strong effect. The invisible rays in which it so much abounds, taken 

 as a whole, appear to be even more refrangible than those which come 

 from the flame of a spirit lamp." I was not, however, prepared for 

 the strong group of lines in the ultra-violet which, after an exposure 

 of one minute and a half, came out upon the plate. 



Two or three weeks later, about the middle of January, 1880, I 

 showed this spectrum to Professor Stokes, and we considered it 

 probable that this remarkable group was the spectrum of water. 

 Professor Stokes permits me to mention that, in a letter addressed to 

 me on January 30, he speaks of " this novel and interesting result," 

 and makes some suggestions as to the disputed question of the carbon 

 spectrum. 



* " Phil. Trans.," 1852, p. 539. 



