2,02 



Of the Propagation of Heat 



Number 



of the 



Experiment. 



No. 45 

 No. 46 



No. 47 

 No. 48 

 No. 49 



Temperature of the Water in 

 the Jar i Inch below its Surface. 



In the begin- 

 ning of the 

 Experiment. 



1 88° 



186 



189 



1S7 

 1 88 



At the end 



of the 

 Experiment. 



68° 



67 



68 



67 



68 



Temperature 



of the cold 



Mixture in 



which the Jar 



was kept 



plunged to its 



brim. 



32 

 32 

 32 

 32 



32 



Time the 



Water 



remained on 



the Ice. 



Minutes. 

 30 

 30 

 30 

 30 

 30 



Quantity of Ice 

 melted. 



Grains. 

 406 



440 

 . 432 



355 

 364 



Quantity of ice melted in these 5 experiments. 



1997 



Mean quantity melted by hot water when the jar was kept 

 plunged to its brim in melting. ice and water 



Mean quantity melted by hot water in 30 minutes, in the two 

 experiments. No. 26 and No. 27, when the part of the jar 

 occupied by the water was surrounded by air, at the tem- 

 perature of 41° ........ 



Mean quantity melted by hot water in 30 minutes, in tbe three 

 experim.ents. No. 39, No. 40, and No. 41, when the part of 

 the jar occupied by the water was surrounded by air, at the 

 temperature of 61° ......•• 



Mean quantity melted by hot water in 30 minutes, in the two 

 experiments. No. 34 and No. 35, when the part of the jar 

 occupied by the water was kept covered up by a thick and 

 warm covering of cotton ....... 



Grains 



3991 



456 



558^ 



690! 



As all the experiments were made in the same man- 

 ner, and with equal care, and differed only in respect to 

 the manner in which the outside of the jar, above the 

 surface of the ice in it, was covered, their results shew 

 the effects produced by those differences. 



I should perhaps have suspected that the greater quan- 

 tity of ice which was melted when the heat of the water 

 in the jar was confined for the longest time had been oc- 

 casioned, at least in part, by the Heat communicated 

 downwards by the medium of the glass ; but that this 

 could not have been the case was evident, not only from 



