GASEOUS SPECTRA UNDER HIGH DISPERSION. 451 



And Dr Hasselberg seems to perform a somewhat similar part for 

 Hydrogen, excepting that there, the high-temperature lines are seen simultane- 

 ously, or together, with those of the low-temperature spectrum. 



Of these three elemental gases, all of them equally and similarly disputed 

 upon, the case of Oxygen is perhaps the most advanced and instructive. 



With simple, direct, uncondensed induction sparks, passing through an 

 Oxygen vacuum tube, every one allows, or will allow I hope after reading this 

 paper, and severely experimenting, that he does, as he should, get that spectrum 

 of minute triplets which I have been describing here at length. And every one 

 also allows, and has allowed it for many years past, that if yon send a suffi- 

 ciently condensed, intensified, jar discharge of induction electricity through the 

 same tube, the spectrum immediately changes to something perfectly different, 

 viz., the high-temperature, or line-spectrum of Oxygen, as set forth on strips 

 Nos. 7 and 8 of our Index Map, Plate LXXVII. 



The facts therefore are allowed, and it is only the interpretation of them 

 which is different with different parties. One side insisting on a different 

 vibration of the same particles of Oxygen, under the two kinds of electric 

 sparks, being the only reason of the two totally different spectra ; and the 

 other declaring that with the milder spark, the Oxygen must have entered into 

 momentary chemical combination with something else that was already in the 

 tube, but unperceived by, and totally unknown to, its owner. 



There is little doubt too that there may be many more infinitesimally small 

 things in a tube, or extractible out of its sides by electric discharge, than 

 chemical philosophy is at present aware of. While even with so gross a 

 matter, as CH in sufficient quantity to give strong spectral bands, — we have 

 seen London scientists going on for years preparing CO, and quite unconscious 

 that they were at the same time manufacturing CH with it, even pari passu. 

 Some particular kinds of gaseous impurity that may be in a tube, adhering to 

 its sides or otherwise, — I have shown in this paper may be easily submerged by 

 greater density of another gas thrown into it. But if that gas be contaminated 

 at its birth with some other, either not yet recognised by Chemistry, or in too 

 small proportions to be detected by any existing chemical method, — who shall 

 help ! There may have to be a new chemistry elaborated, dealing with infinite- 

 simally small combining quantities. But that is something so hazardous to 

 count upon, that we may well in the meantime accept the varying temperature 

 vibration theory, as a mere method of classification ; and then we shall find that 

 there is an immense deal yet to be done, in order to collect even the plain and 

 practical facts of the spectra of the best known gases, in such degree of purity 

 as they can be prepared in, at present. For with every elemental and permanent 

 gas, i.e., gaseous at all known temperatures and moderate pressures, — there 

 seem to be three different temperatures under which its spectrum in some 



