OF RADIANT HEAT THROUGH DIFFERENT BODIES. 37 
the different luminous rays, and thus throws certain quantities of heat 
on the very spaces occupied by the different colours of the spectrum ; 
but that in the coloured glasses and, generally, in bodies more or less 
diathermanous, the absorbent force does not act in the same manner as 
the force of refraction, which sometimes extinguishes more heat than 
light and at others more light than heat. 
But those who maintain the identity of the two agents will reply, that 
the differences observed in the calorific and luminous transmissions of 
the diaphanous or coloured media are produced by rays of obscure 
heat which mix i great quantities with the rays of light emitted by 
the flame. 
In order to decide how far it is allowable to maintain the one or the 
other hypothesis, we should have data which, at present, are not within 
ourreach. We shall resume this subject at the end of the next Memoir, 
and conclude the present one with an account of a very remarkable ap- 
plication of the numerical results contained in the foregoing tables.’ 
It had been established by the beautiful experiments of Seebeck that 
the place of the maximum of temperature in the solar spectrum varies 
with the chemical composition of the substance of which the prism is 
made. This eminent philosopher observed that the highest degree of 
heat which, in the spectrum furnished by a prism of crown glass, was 
in the red, passed to the orange when the prism employed was a hollow 
glass one filled with sulphuric acid, and was found in the yellow when 
the same prism was filled with pure water*. 
I discovered some months since that the caloric rays scattered on the 
colours given by a common prism do not undergo the same alteration 
in passing through a layer of water; the loss varies inversely as the re- 
frangibility, so that the most refrangible rays pass undiminished and the 
least refrangible are entirely stopped by the liquid +. 
This experiment led to a very simple explanation of the results ob- 
tained by Seebeck. 
The solar heat which presents itself to the anterior face of the prism 
of water contains rays of every degree of refrangibility. Now the ray 
which has the same index of refraction as the red light, suffers in pass- 
ing through the prism a loss porportionally greater than the ray which 
possesses the refrangibility of orange light, and less is lost by the latter 
in the passage than by the heat of the yellow ray. These increasing 
fatios in the losses of heat sustained by the less refrangible rays have 
an evident tendency to transfer the maximum to the violet. It may 
therefore be stopt at the yellow. 
* Schweigger’s Jahrbuch der Chemie und Physik, vol. x. [A translation of 
the memoir of Seebeck here referred to will be found in the Philosophical Ma- 
gazine, first series, vol. Ixvi. p. 330, ed seg.—Enir. ] 
+ Annales de Chimie et de Physique, Décembre 1831. 
