CELESTIAL CHEMISTRY. 231 



SPECTRUM OF COMET I., 1866. 



Mr. William Huggins, F.R.S., examined the light both of the 

 nucleus and of the coma of the small telescopic comet which was 

 visible during a part of January last, and which is catalogued by 

 the astronomers as Comet I., 1866, by the aid of the sijectrura 

 apparatus with which he made his well-known observations on 

 the spectra of the uebuliB. His observations have led him to the 

 conclusions that the nucleus of that comet is self-luminous, and 

 that it consists of gaseous matter in a state of incandescence, but 

 that the coma is not self-luminous, and that the reflected light by 

 which the coma was rendered visible to us was the light of the 

 sun. The spectrum of the nucleus, like the spectra of several of 

 the nebulae previously examined by Mr. Huggins, consisted of 

 but one bright line, corresponding in refrangibility with the 

 brightest of the lines of nitrogen. The exact similarity between 

 the spectrum of this comet and spectra of the nebulae in question, 

 implies the existence of some very close relation between comet- 

 ary and nebulous matter, while the identity of the single line 

 presented by these specti'a with one of the nitrogen lines would 

 seem to suggest the hj'pothesis that nitrogen is not an elementary 

 substance, but a compound one, and that it is of some one of the 

 several constituents, which thus go to make up what we know as 

 nitrogen, that this nebulous and cometary matter consists. — Me- 

 chanics'' Magazine, March, 1866. 



SPECTRUM OF SIRIUS. 



Father Secchi has just announced that the space in the spec- 

 trum of Sirius, which is included between the extreme red and 

 the first band, is " divided by small l>ands, sensibly equi-distant," 

 which small bands are of such extreme regularity as to give to 

 the spectrum a " channelled" appearance. He counted twenty- 

 eight of these small bands, nothing similar to which has yet been 

 observed in any other spectrum. 



SPECTRUM OF SHOOTING STARS. 



Mr. A. S. Herschel has recently observed the spectrum of a 

 shooting star. It ai)peared near Capella, and was almost as 

 brilliant as that star. He followed it for more than a second in 

 its rather slow motion, and ascertained that its spectrum was as 

 continuous a spectrum as that of Capella, and a little more ex- 

 tended, and, therefore, that it consisted of a solid or liquid sub- 

 stance, and not of a gas or incandescendent vapor, as Mr. Huggins 

 has suggested with regard to some nebulae. 



He has observed seventeen meteors, coming to the conclusion 

 that " if the problem of chemically analyzing the substance of 

 luminous meteors by means of their light spectra is not yet fairly 

 solved, it is at all events pretty certain that the metal sodium 

 produces the most endui'ing light of the much admired trains of 

 the August meteors ; and that at least one other mineral substance 



