Mr. J. N. Lockyer's Spectroscopic Notes. 233 



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 represented by the addition of a system 

 of well-defined " beats " aud 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 den- 

 sity 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. 



" Spectroscopic Notes. — No. II. On the Evidence of Yariation 

 in Molecular Structure." By J. Norman Lockyer, F.R.S. 



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 spectro- 

 scope 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 constituent 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. 



6. The spectroscope supplies us with intermediate stages between 

 these extremes. 



(a) The spectra vary as we pass from the induced current with 

 the jar to the spark without the jar, to the voltaic arc, or to the 

 highest temperature produced by combustion. The change is always 

 in the same direction ; and here, again, the spectrum we obtain 

 from elements in a state of vapour (a spectrum characterized by 

 spaces and bands) is similar to that we obtain from vapours of 

 which the compound nature is unquestioned. 



((3) At high temperatures, produced by combustion, the vapours of 

 some elements (which give us neither line- nor channelled space- 



