372 Mr. J. N. Lockyer's Spectroscopic Notes. No. II. [June 11, 



Only the longest " fundamental " line was absorbed. 



The line was thicker than the D line in the solar spectrum, in ivhich spec- 

 trum all the short lines are reversed. 



2. As it was difficult largely to increase either the temperature or the 

 density of the sodium-vapour, I have made another series of experiments 

 with iodine-vapour. 



I have already pointed out the differences indicated by the spectro- 

 scope between the quality of the vibrations of the " atom " of a metal 

 and of the " subatom " of a metalloid (by which term I define that mass 

 of matter which gives us a spectrum of channelled spaces, and builds up 

 the continuous spectrum in its own way). Thus, in iodine, the short lines, 

 brought about by increase of density in an atomic spectrum, are repre- 

 sented by the addition of a system of well-defined " beats " and broad 

 bands of continuous absorption to the simplest spectrum, which is one 

 exquisitely rhythmical, the intervals increasing from the blue to the red, 

 and in which the beats are scarcely noticeable.. 



On increasing the density of a very small thickness by a gentle 

 heating, the beats and bands are introduced, and, as the density is still 

 further increased, the absorption becomes continuous throughout the 

 whole of the visible spectrum. 



The absorption of a thickness of .5 feet 6 inches of iodine-vapour at a 

 temperature of 59 F. has given me no indication of bands, while the 

 beats were so faint that they were scarcely visible. 



VI. " Spectroscopic Notes. No. II. On the Evidence of Varia- 

 tion in Molecular Structure." By J. NORMAN LOCKYER, F.R.S. 

 Received May 26, 1874. 



1. In an accompanying note I have shown that when different degrees 

 of dissociating power are employed the spectral effects are different. 



2. In the present note I propose to give a preliminary account of some 

 researches which have led me to the conclusion that, starting with a mass 

 of elemental matter, such mass of matter is continually broken up as the 

 temperature (including in this term the action of electricity) is raised. 



3. The evidence upon which I rely is furnished by the spectroscope in 

 the region of the visible spectrum. 



4. To begin by the extreme cases, all solids give us continuous spectra; 

 all vapours produced by the high-tension spark give us line-spectra. 



5. Now the continuous spectrum may be, and as a matter of fact is, 

 observed in the case of chemical compounds, whereas all compounds 

 known as such are resolved by the high-tension spark into their consti- 

 tuent elements. We have a right, therefore, to assume that an element 

 in the solid state is a more complex mass than the element in a state of 

 vapour, as its spectrum is the same as that of a mass which is known to 

 be more complex. 



