120 Count Rumford’s Enquiry concerning the Nature of Heat , 
beater’s skin had been removed to a distance from the ball to 
which it was presented, which was Jive times greater than the 
distance at which the other vessel was placed from the opposite 
ball. 
I was induced to conclude, from the result of this interesting 
experiment, that an animal substance emits 25 times more 
calorific rays, than a polished metallic surface of the same di - 
mensions, both substances being at the same temperature. 
Exper. No. 22. Having emptied both the vessels used in the 
last experiment, and refilled them with pounded ice and water, 
I now presented them again to the thermoscope, at equal dis- 
tances from their respective balls. 
The result of this experiment confirmed the conclusion I had 
been induced to draw from a former experiment of the same 
kind, (No. 13,) the motion of the bubble towards the vessel 
whose surface was covered with gold-beater's skin, showing that 
the rays which proceeded from that animal substance were con- 
siderably more efficacious in producing cold, than those which 
proceeded from the naked metal. 
The radiation of cold bodies appearing to me to have been 
proved beyond all doubt, by the preceding experiments, I now 
set about to investigate a very important point, which still re- 
mained to be determined : I endeavoured to find out, whether the 
intensity of the action of the frigorific rays which proceed from 
cold bodies, or their power of affecting the temperatures of other 
warmer bodies, at equal intervals of temperature , is, or is not, 
equal to the intensity of the action of the calorific rays which 
proceed from hot bodies. To ascertain this point, I made the 
following very simple and decisive experiment. 
Exper. No. 23. Having placed the thermoscope on a table, in 
