OF THE SOLAR SPECTRUM. 555 
trum during a few seconds on the surface, then we again close 
the aperture of the shutter, and immediately raise the tempera- 
ture to two or three hundred degrees ; then the parts which have 
been affected by the phosphorogenic rays become strongly lumi- 
nous, whilst the other portions corresponding to the dark lines 
remain perfectly black. 
_ By employing greater or lesser spectra, or at least parts of the 
“spectrum more or less enlarged, I have proved the existence of 
the same lines in the spectrum formed by these rays as in the 
luminous and chemical spectra; it is therefore useless to repre- 
it them ; they are easily distinguished in the most refrangible 
ys, but more difficult in the less refrangible rays, for they are 
s distinct. 
If attention be paid to the facts which I related when I began 
speak of phosphorescence, before mentioning the lines, we 
see that with rays situated beyond the visible rays, that is to 
Say with obscure rays, light is produced, since the sulphurets 
become phosphorescent under their influence, and that after- 
wards, in causing some of the luminous rays—red, orange, yellow, 
green, blue—to fall upon them, we destroy this faculty, and the 
ies become dark. 
> g IV. 
seve to the results which I have related in this memoir, 
we see that, by the chemicai and phosphorogenic radiations which 
upon any sensible substances whatever, if each part of simi- 
r refrangibility of these different spectra is considered, we find 
versed by the same lines or spaces without rays, as the 
corresponding part in the luminous spectrum. It is therefore 
‘probable that the rays of similar refrangibility are absorbed at 
the same time by the different substances through which they 
pass, and that the cause which occasions the absence of certain 
Yays in the solar light is also that which produces the disappear- 
ance of these rays in the other radiations. 
I have not yet quite resolved the question relative to the radi- 
ant heat and the determination of the lines in the calorific spec- 
| tum, but I am at present engaged on this subject, and I hope 
shortly to publish all the results to which these researches will 
have led me. 
It has been generally admitted that these radiations which 
aecompany light are different from each other, and that, accord- 
