2 92 Of the Propagation of Heat 



on its being poured into the jar having subsided, we 

 may suppose the process of melting the ice to have gone 

 on regularly. 



But if in the regular course of the experiment no 

 more than 2620 grains were melted in 170 minutes, it is 

 evident that not more than 154 grains could have been 

 melted in the ordinary course of the process in 10 min- 

 utes ; for 170 minutes : 2620 grains : : 10 minutes : 154 

 grains. If, therefore, from 580 grains, the quantity of 

 ice actually melted in 10 minutes in the 25th experi- 

 ment, we deduct 154 grains, there remains 426 for the 

 quantity melted in pouring the water into the jar. 



Let us see, now, how far this agrees with the result of 

 the 26th experiment. In this experiment 914 grains of 

 ice were melted in 30 minutes. If from this quantity we 

 deduct 426 grains, the quantity which, according to the 

 foregoing computation, must have been melted in pouring 

 the hot water into the jar ', there will remain 478 grains for 

 the quantity melted in the ordinary course of the process 

 in 30 minutes; which gives 159 grains for the quantity 

 melted in 10 minutes ; which differs very little from the 

 result of the foregoing computation, by which it ap- 

 peared to be = 154 grains. This difference, however, 

 small as it is, is sufficient to prove an important fact, 

 namely, that the effects produced by the motion into 

 which the hot water had been thrown in being poured 

 into the jar had not ceased entirely in 10 minutes, or 

 when an end was put to the 25th experiment. We shall 

 therefore come nearer the truth, if, in our endeavours to 

 discover the quantity of ice melted in any given time in 

 the ordinary course of the experiments, we found our 

 computation on the results of the two experiments No. 

 26 and No. 27. 



