Undoubtedly they would. But the various bodies in the room would not, at a lower temperature, furnish either of the canisters with a sufficiency of caloric to compensate for the loss they undergo; for, suppose the black canister to absorb 400 rays of caloric, whilst the metallic one absorbed only 200; yet if the former radiate 800, whilst the latter radiates only 400, the black canister will be the first cooled down to the temperature of the room. But from the moment the equilibrium of temperature has taken place, the black canister, both receiving and giving out 400 rays, and the metallic one 200, no change of temperature will take place.
EMILY.
I now understand it extremely well. But what becomes of the surplus of calorific rays, which good radiators emit and bad radiators refuse to receive; they must wander about in search of a resting-place?
MRS. B.
They really do so; for they are rejected and sent back, or, in other words, reflected by the bodies which are bad radiators of caloric; and they are thus transmitted to other bodies which happen to lie in their way, by which they are either absorbed or again reflected, according as the property of reflection, or that of absorption, predominates in these bodies.
CAROLINE.
I do not well understand the difference between radiating and reflecting caloric, for the caloric that is reflected from a body proceeds from it in straight lines, and may surely be said to radiate from it?
MRS. B.
It is true that there at first appears to be a great analogy between radiation and reflection, as they equally convey the idea of the transmission of caloric.
But if you consider a little, you will perceive that when a body radiates caloric, the heat which it emits not only proceeds from, but has its origin in the body itself. Whilst when a body reflects caloric, it parts with none of its own caloric, but only reflects that which it receives from other bodies.