1880.] On the Spectrum of the Flame of Hydrogen. 579 



light from this part of the flame was projected upon the slit. The 

 spectrum, No. 3 in the diagram, contains the water group already 

 described, and in addition a very strong line close to Gr, and two 

 lines, X 3872 and X 3890 ; this latter line is seen to be the more refran- 

 gible limit of a group of fine lines shading off towards K. 



The ultra-violet group when carefully compared with the group in 

 the spectrum of pure hydrogen, shows several small differences. I 

 am inclined to believe that there is the superposition of a second 

 fainter group. There is strong evidence of this in some spectra of 

 hydrogen taken under other conditions. There is also a broad band 

 less refrangible than the strong line at Gr, and the light extends from 

 this line on its more refrangible side. 



A double Bunsen burner (Fletcher's form) with a strong blast of 

 air was then fitted up. The spectrum was taken of the intense blue 

 flame. It resembles the one last described. All the distinctive fea- 

 tures are intensified, and a continuous spectrum and groupings of 

 very fine lines fill up all the intervals between the groups already 

 described, so that there is an unbroken strong spectrum throughout 

 the whole region which falls upon the plate. 



A spirit lamp was arranged before the slit. The spectrum is essen- 

 tially the same as No. 3, but as it is less intense only the strongest 

 lines are seen. The water group, the strong line at Gr, and the pair 

 of lines rather more refrangible than K, are seen. Probably with a 

 longer exposure the finer lines would also show themselves. 



The distinctive features of spectrum No. 3 appear to be connected 

 with the presence of carbon. 



Table of Wave-lengths of the Principal Lines of the Spectrum of 

 Water. No. 1. 



3062 



3095 



3135 



3171 



3217-5 



3068 



3099 



3139 



3175 



3223 



3073 



3102 



3142-5 



3180 



3228 



3074 



3105 



3145 



3184 



3232 



3077-5 



3111 



3149'5 



3189 



3242-5 



3080 



3117 



3152-5 



3192-5 



3252-5 



3082 



3122-5 



3156 



3198 



3256 



3085 



3127 



3159-5 



3201 



3262 



3090 



3130 



3163 



3207-5 



3266 



3094 



3133 



3167 



3211 



3276 



VOL. XXX, 



