W. Huggins—Spectrum of the Flame of Hydrogen. 121 
Art. XVII.—On the Spectrum of the Flame of Hydrogen ; by 
WituiaAM Huaerns, 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, that théy have obtained a photo- 
graph of the ultra-violet part of the spectrum of coal gas burn- 
ing in oxygen, and in a note dated June 8th 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 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 inves- 
tigation is more complete. 
On December 27, 1879, I took a photograph of the flame of 
hydrogen burning in air. As is well known, the flame of hy- 
drogen 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. 
rofessor Stokes, in his paper ‘ On the Change of Refrangi- 
bility of Light,”’* has stated that ‘the flame of hydrogen pro- 
uces a very strong effect. The invisible rays in which it so 
much abounds, taken as a whole, appear to be even more re- 
frangible than those which come from the flame of a spirit 
amp.” I was not, however, prepared for the strong group of 
dines in the ultra-violet which, after an exposure of one minute 
and a half, came out upon the plate. 
wo or three weeks later, about the middle of January, 
1880, I showed this spectrum to Professor Stokes, and we con- 
sidered 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 80, he speaks of “ this novel 
and interesting result,” and makes some suggestions as to the 
ote question of the carbon spectrum. 
have since that date taken a large number of photographs of 
the spectra of different flames, in the hope of being able to pre- 
. Sent the results to the Royal Society, when the research was more 
complete. I think now that it is desirable that I should de- 
seribe the spectrum of the flame of hydrogen, but I shall reserve 
for the present the experiments which alae to the presence of 
carbon and its compounds, 
The spectrum of the flame of hydrogen burning in air (No. 1) 
consists of a group of lines which terminates at the more re- 
frangible limit in a pair of strong lines, 4 3062 and A 3068. At 
a short distance, in the less refrangible direction, what may 
* Phil. Trans, 1852, p. 539. 
