r 125 ] 
creating their heat. The greateft degree 
of heat the firfl time was 130°. He ex- 
pofed himfelf to it, and was able to 
remain in it fifteen minutes. The furface 
of his bodv was covered with fweat, and 
the thermometer placed under the tongue 
flood at ioo°. 
He increafed the heat to 214 0 , which 
he was capable of fuftaining for a quarter 
of an hour. The thermometer flill did 
not exceed 1 oo°. 
A dog can live in air heated to 260° for 
a confiderable time, and yet retain its own 
temperature. From other experiments 
which the author has made, it appears, 
that in living animals the power of refilling 
heat does not arife folely from evapora¬ 
tion, and that certain animals, as frogs 
for inftance, receive heat more flowly 
when living than when dead. 
Thus have animals a power of genera¬ 
ting caloric, and if we may fo fay, con- 
centra- 
