Spectrum of Aqueous Vapor. 



229 



hydrogen bands maj 7 be narrowed and rendered lines in a spec- 

 trum of small dispersion such as astrophysicists are compelled 

 to employ, by an electrical dissociation of water vapor in the 

 presence of an excess of oxygen, and that these new lines may 

 thus be evidence of the presence of aqueous vapor in the stars 

 of this new type. To test this theory I filled a tube with 



oxygen, and submitted it to a powerful condenser discharge. 

 The resulting spectrum was of the general type obtained by 

 these strong discharges in hydrogen, rarified air and nitrogen. 

 It is shown in fig. 3, No. IV. If we compare this spectrum 

 with I, in which the broad bands represent hydrogen lines 

 in hydrogen at atmospheric pressure ; with II, the spectrum 

 of rarified air ; also with the lower one in III, the spectrum 

 obtained in pure nitrogen, we see that the main hydrogen 

 lines are narrower and certain hydrogen lines are so faint as to 

 be hardly visible even on the negative. 



The general character of the spectral lines of hydrogen in 

 respect to breadth and intensity seems not to depend so much 



