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II. On the Spectrum of the Oxy-hydrogen Flame. 



By G. D. LIVEING, M.A., F.R.S., Professor of Chemistry, and J. DEWAK, M.A., 

 F.R.S., Jacksonian Professor, University of Cambridge. 



Received January 18, Bead February 2, 1888. 



[PLATES 1-4.] 



IN 1880 we described, simultaneously with Dr. HUGGINS, a series of linen furining the 

 strongest part of the spectrum of water, and again, in 1 882, a second, less strong and more 

 refrangible series, forming a second section of the same spectrum. Subsequently, 

 M. DESLANDRES discovered a third still weaker and more refrangible series, beginning 

 at a wave-length 2610*3. We find, however, that the spectrum does not end there, 

 but extends both on the more refrangible and on the less refrangible sides to a con- 

 siderable distance. By employing a large spectroscope with a single calcite prism and 

 a long exposure we have obtained photographs of the spectrum of the oxy-hydrogen 

 flame, showing closely set lines from wave-length 2268 to 4100, with traces of lines 

 beyond those limits. The whole spectrum appears to consist of a succession of 

 rhythmical series of lines, the lines of each rhythmical series being stronger and more 

 closely set at the more refrangible end of the series and becoming weaker and wider 

 apart towards the less refrangible end. The strongest of these series are those first 

 described, those on either side of them becoming fainter as they are more remote, 

 until the highest series gave us a measurable photograph only after an exposure of 

 five hours. In most cases two series begin near together and overlap one another, 

 producing a complication which cannot easily be unravelled, and the overlapping 

 appears in some cases to extend to more than two series. 



M. DESLANDRES states (' Comptes Rendus,' vol. 100, p. 854,) that the first band 

 of the water spectrum (i.e., the group beginning at a wave-length about 3063) 

 includes a series of rays which reproduce, line for line, at the same distances and with 

 the same relative intensities, the band A of the solar spectrum ; and that the second 

 band (i.e., the group beginning at a wave-length about 2811) includes a series corres- 

 ponding to B, and that in the third a may be found to be reproduced. He does 

 not state at what wave-lengths in these bands we are to look for the more refrangible 



E 2 i.r,.8 



