127 - 
and the Mode of its Communication . 
from the results of the two last experiments, we have abundant 
reason to conclude, that they will be just as efficacious in heating 
the former, as in cooling the- latter. 
Before I proceed to give an account of the experiments which 
were made with a view to determine the relative quantities of 
rays emitted from the surfaces of various substances, from living 
animals, dead animal matter, &c. (which I must reserve for a 
future communication,) I shall lay before the Society the results 
of several experiments, of various kinds, which were made with 
a view to the farther investigation of the radiations of hot and 
of cold bodies, and of the effects produced by them. 
Exper . No. 25. Having found, from the results of the expe- 
riments No. 21 and No. 22, that great quantities of rays are 
thrown off from the surface of the animal substance used in 
those experiments, (gold-beater's skin,) I now covered the whole 
of the external surface of one of my large cylindrical passage 
thermometers (No. 4) with that substance ; and, filling it with 
boiling hot water, exposed it to cool gradually in the air of a 
large quiet room, in the manner often described in former parts 
of this Paper; another similar naked standard instrument (No. 3) 
being filled with hot water at the same time, and exposed to 
cool in the same situation. 
The temperature of the air of the room being 51 the in- 
struments were found to cool through the standard interval of 10 
degrees, namely, from ioi-§- to 91^, in the following times. 
No. 4, covered with gold-beater's skin, in 27^ minutes. 
No. 3, which was naked, - - in 45 minutes. 
Exper. No. 2 6. Being desirous of finding out whether or not 
the covering of animal matter, which had so remarkably facili- 
tated the cooling of the instrument No. 4, would be equally 
