r64 I.xperiiuenls Jhcwiiig thai Cold Wjttr, rtpofing 



As foon as the operation of pouring the hot water into the jar was finifiieil, the perforated 

 dilh was carefully removcil, and the jar was covered with a circular wooden cover, from the 

 ccnttc of which a fmall mercurial thermometer was fufpended. The irregularities of the 

 experiments were greatly diminidied by the expedient of the wooden difli. One more im- 

 provement however was added to the manipulation. It confifted in pouring 8[ cubic inclics 

 of ice-cold water upon the ice in the jar, previous to the introdudlion of the wooden dilii. 

 This water covered the furf.ice to the height of 0,478 of an inch. 



Much as I could have wilhed to relate the whole of the intcreding experiments in thii 

 cfTay, tiie requifite attention to brevity in this abridgment lias made it ncccd'ary to omit 

 every matter of fubordinatc detail. For the fame reafon I forbear to ftate the refults af- 

 forded by the two fird methods of trial. Thofe with the complete apparatus were as fol- 

 lows ; the temperature of the room being 41 degiccs. 



From the refults of thefe three experiments, the Count proceeds to determine how much 

 ice was melted in the aci of pouring the -water into the jar-, and confequently the rate at which 

 it was melted in the ordinary courfe of the experiment ; fuppofing equal quantities to be 

 melted in equal times. I give the rcafoning in his own words. 



As in the 27th experiment 3200 grains were melted in i8o minutes, and in the 25th 

 experiment 580 grains were melted in 10 minutes, we may fafely conclude that the fame 

 quantity mud have been melted in the fame time (to minutes) in the 27th experiment. If 

 therefore from 3200 grains, the quantity melted in 180 minutes in this lafl e.\pcriment, we 

 deduil 580 grains for the quantity melted during the firft ten minutes, there will remain 

 2620 grains for the quantity melted in the fueeeeding 170 minutes, when, the motions oc- 

 cafioncd in the water on its being poured into the jar having fubfideil, we may fuppofe tl;c 

 proccfs of melting the ice to have gone on regularly. 



But if in the regular courfe of tiie 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 courfe of the procefs in ten minutes; for 170 minutes : 2620 grains : : 10 minutes : 

 154 grains. If therefore from 580 grains, the quantity of ice aiftually melted in ten 

 4iiinutes in the 25th experiment, we deduct 154 grains, there remains 426 for the quantity 

 melted in pouring the water into the jar. 



Let us fee now how far this agrees with the refult of the 26th cxpciiment. In this ex- 

 periment 914 grains of ice were melted in 30 minutes. If from this quantity we dedurt 

 426 grains, the quantity which, according to tlie foregoing computation, muft have been 

 3 melted 



