And the result, I think, is very conclusive.
MRS. B.
The experiment may be repeated with a wax taper instead of the bullet, with a view of separating the light from the caloric. For this purpose a transparent plate of glass must be interposed between the mirrors; for light, you know, passes with great facility through glass, whilst the transmission of caloric is almost wholly impeded by it. We shall find, however, in this experiment, that some few of the calorific rays pass through the glass together with the light, as the thermometer rises a little; but, as soon as the glass is removed, and a free passage left to the caloric, it will rise considerably higher.
EMILY.
This experiment, as well as that of Dr. Herschell’s, proves that light and heat may be separated; for in the latter experiment the separation was not perfect, any more than in that of Mr. Pictet.
CAROLINE.
I should like to repeat this experiment, with the difference of substituting a cold body instead of the hot one, to see whether cold would not be reflected as well as heat.
MRS. B.
That experiment was proposed to Mr. Pictet by an incredulous philosopher like yourself, and he immediately tried it by substituting a piece of ice in the place of the heated bullet.
CAROLINE.