OF THE SOLAR SPECTRUM. 549 
rays which act in an inverse manner to the preceding, the maxi- 
mum of action being at F. 
From all that I have shown in this section we may conclude, 
_ that for all the substances sensible to the action of the solar rays, 
the lines of the chemical spectra which act on these substances 
are the same as the lines of the luminous spectrum, when we 
only consider the corresponding spaces. Moreover, as generally 
happens for many substances, the chemical action extends much 
beyond the extreme violet. There are an infinite number of lines 
which are the same for all the spectra, and which we have repre- 
‘sented at their respective distances (fig. 10). 
.The chemical action, in certain cases, may extend beyond the 
red, but it is very difficult to represent the lines beyond a, for 
they are very confused by projection; on the contrary, beyond 
the violet they are very numerous and very distinct. The mode 
of performing the experiment, then, makes us acquainted with 
_ the constitution of the solar spectrum beyond the visible parts, 
“2 
and that as far as a distance equal to the half of the length of 
_ the luminous spectrum. 
We employed only a prism of very pure flint-glass in our ex- 
_ periments, but the effects would be the same if other prisms were 
used; the reason for this is as follows:—In the first place, 
Fraunhofer found that the nature of the lines in the luminous 
spectrum was independent of the substance of the prism, only 
their respective position changed a little from the greater or less 
dispersion of this prism. In the next place, in a memoir which 
I published on the electric effects accompanying the chemical 
_ action of light, and on the use of the electro-chemical actinometer, 
I showed that by employing a prism of glass, of water, of alum, or 
_of rock-salt, results were obtained which varied but little relative 
_ tothe chemical rays. Thus the conclusions which we have above 
announced are exact in all their generality. 
§ III. On the Phosphorogenic Spectrum. 
If there are any phenomena which excite the attention to a 
high degree when they are studied with care, these are certainly 
the phenomena of phosphorescence. Everything seems to prove 
that their origin is electric, and, in fact, most of the causes which 
_ disturb the molecular equilibrium of bodies seem to give rise to 
these phenomena. Thus all bodies which are non-conductors 
_ of electricity, if they are not phosphorescent after a short expo- 
