﻿458 Mr. W. Huggins on some Spectrum 



comets — a difference sufficiently great to support the conclusion 

 that the conditions in the two comets by which the light was 

 furnished were not identical. The first band occurs about half- 

 way from D to E of the solar spectrum ; the second band begins 

 about b and extends nearly to F. The third band presents itself 

 between E and G. 



The three broad cometary bands differ greatly in refrangibility 

 and in character from the sharply defined narrow lines of the 

 nebulse, and appear to show a constitution distinct from that 

 of the nebulse. 



The morning after I had made the observations of Winnecke's 

 comet, I was much interested to find that the comet's spectrum 

 appeared to be identical with one of a series of the spectra of 

 carbon, as obtained from the decomposition by the induction- 

 spark of several compounds of carbon which I had prepared 

 some years before. 



The modification of the spectrum of carbon, which appeared 

 identical with the cometary spectrum, presented itself when the 

 spark was taken in olefiantgas and some other compounds of car- 

 bon, and differs from the apparently more perfect spectrum which 

 is obtained by the decomposition of cyanogen and olive-oil, &c, 

 in the one circumstance alone that the three bands in the bright 

 parts of the spectrum are not resolved into distinct narrow lines, 

 but the light in each band becomes gradually fainter without suf- 

 fering any break in its continuity. 



I believe we have a right to consider this peculiar spectrum, 

 containing the three bright bands, to be the spectrum of the 

 vapour of carbon and not that of any stable hydrocarbon, for the 

 reason that I obtained the same spectrum when I used olive-oil, 

 the vapour of Persian naphtha in hydrogen, and other hydrocar- 

 bons, as when I employed cyanogen. In one case the spectrum 

 was accompanied by the lines of hydrogen, in the other by the 

 known complex spectrum of nitrogen. A spectrum essentially 

 the same, though less complete, was obtained, together with the 

 known lines of oxygen, when carbonic acid and carbonic oxide 

 were employed. 



In the evening of the same day I compared the spectrum of 

 the comet directly with the spectrum of olefiant gas, the two 

 spectra being juxtaposed in the instrument. Careful compari- 

 sons made on that evening, when my friend Dr. W. Allen Miller 

 observed with me, and on two subsequent nights, showed that 

 in every particular of refrangibility and of relative intensity, the 

 spectrum of the comet was similar to that of carbon. 



The obvious and apparently well-founded conclusion from 

 these observations would be that the cometary matter from which 

 this light comes consists of the luminous vapour of carbon. 



