EKpsrimenfs on the Fufim «f Ice. 34 j 



"WlTien one hour and 30 minutes (reckoning always from the time when the boilttig 

 \<rater was poured into the jar) had elapfed, the heat of the water in the middle of the jar 

 was found to be as follows : 



Degrees. 

 At the furface of the ice — — ^ — 40 



1 Inch above it . — 84 



2 Inches — __ . __ up 



3 Inches . — 116 



7 Inches ___ _i u^ 



. When two hours had elapfed, the heat in the middle of the jar was found to be as 

 follows : 



Degrees. 

 At the furface of the ice — ■ — . 40 



1 Inch above it — ^5 



2 Inches —^ ___ — p^ 



3 Inches — _ 106 



4 Inches — log 



6 Inches -^ 108J, 



7 Inches — Io8| 



An end being now put to the experiment, the hot water was poured off from the ice ; 

 and on weighing that which remained, it was found that five ounces fix grains troy ( = 2406 

 grains) of ice had been melted. 



Taking the mean temperature of the water at the end of the experiment at 106°, our 

 author remarks that the mafs of hot water (which weighed 73;^ ounces) was cooled 78 de- 

 grees, or from the temperature of 184° to that of 106° during the experiment. Now as 

 it is known that one ounce of ice abforbs juft as much heat in being changed to water as 

 one ounce of water lofes in being cooled 140 degrees, it is evident that one ounce of water 

 which is cooled 78 degraes, gives off as much heat as would be fufficient to melt t-b^'is of 

 an ounce of ice ; confequently the 73 J ounces of hot water. which in this experiment were 

 cooled 78 degrees, a£lually gave off as much heat as would have been fufficient to have 



melted — — = 40ttt ounces of ice. 



40 



But the quantity of ice a£lually melted was only about five ounces ; and hence it ap- 

 pears that lefs than one-eighth part of the heat loft by the water was communicated to the 

 ice, the reft being carried off by the air. 



As the fame quantity of hot water was ufed in this experiment and in that which im- 

 mediately preceded it, and as this water was contained by the f.ime veffcl, it appears that 

 ice melts more than eighty times flower at the bottom of a mafs of boiling-hot water than 

 when it is fuffercd to fwim on its furface. For as in the one experiment loj ounces of 

 ice were melted in two minutes and 58 feconds, five ounces at leaft mufthavc been melted 

 in one minute and 29 feconds; but in the other experiments two hours or 120 minutes 

 were employed in melting five ounces. 



Vol. I. — November 1797. Y y The 



