38 Inquiry concerning the Nature of Heat, 



with hot water, and observed the times of their cooling 

 as before. 



Result, or time of cooling 10 degrees, reckoned from 

 the 50th to the 4Oth degree above the temperature 

 of the air in which the instruments were exposed to 

 cool : 



Instrument No. I, sides naked, . . . . -55 m i n - 

 Instrument No. 2, sides covered with one coating of glue, 431 " 



When we consider this experiment with attention, 

 we shall find reason to conclude, that if it were by facili- 

 tating the approach and temporary contact of a succes- 

 sion of fresh particles of the cold air of the room to the 

 surface of the glue (which was now in fact become the 

 surface of the hot body), that the cooling of the instru- 

 ment was accelerated, the metal being as completely 

 covered, and the air, supposed to be attached and fixed 

 to its surface, as completely excluded by one coating of 

 the glue as it could be by two or more, two coatings 

 could not possibly accelerate the cooling of the instru- 

 ment more than one ; but if, on the other hand, the 

 cooling of the instrument in this experiment was ac- 

 celerated, not by facilitating and accelerating the mo- 

 tions of the circumambient cold air, but by facilitat- 

 ing and increasing those radiations which are known to 

 proceed from hot bodies, I conceived that two coat- 

 ings of the glue might possibly accelerate the cooling 

 of the vessel more than one. In order to put this con- 

 jecture to the test, I made the following decisive experi- 

 ment. 



Experiment No. 3. I now gave the instrument No. 2 

 a second coating of glue; and, when it was thoroughly 

 dry, I repeated the experiment last mentioned, with the 



