360 Count Rumford on the 
eighty times flower at the bottom of a ma/s of boiling-hot was 
ter than when fwimming on its Surface. ; 
But the ice was melted, though flowly, at the bottom of 
the hot water, which the author accounts for in’ a fatif- 
factory manner without needing to abandon his hypothefis. 
Frefh water prefents an exception to the general law of con- 
denfation by cold: it condenfes in cooling till it comes to 
40°, but on cooling it lower it expands, and continues to 
expand till it freezes and after it has become ice*. Water 
in contact with melting ice is always at the ternperature of 
32°, and therefore fpecifically lighter than that which is 
8 degrees warmer, or at 140°: the latter will therefore 
defcend, being heavier, and by its greater heat melt a portion 
af the ice, be cooled, and then give place to the defcending 
currents of warmer water which fucceed it. It appears toa 
from the experiments which followed, that a confiderable 
portion of the ice that wes melted, was melted in confe- 
quence of the motions into which the water was thrown on 
being poured into the jar. 
The experiments on whieh the author builds his refults 
were conduéted in the following manner: 43°87 cubic 
inches, or 11b, 11! 0z. Troy of water was put into the jar 
efcd, fig. 3, which was placed in an earthen bowl and fur- 
rounded with a freezing mixture compofed of ice and com- 
mon fea falt, by which means the water in the jar was 
frozen into one compact mafs adhering to its bottom and. 
fides. The jar was then removed from the freezing mixture, 
and placed in a mixture of pounded ice and water for 4h. 
that the cake of ice might be brought to the temperature of 
32°, when the furface of the ice, cd, was covered to the 
height of 0478 of an inch with ice cold water before pour- 
ing-im the boiling» water. Inftead of a piece of paper as 
before, a wooden dith perforated with many hundreds of 
* Salt water on the contrary continues to be condenfed the more, the 
more it is cooled. . 
holes 
. 
; 
F; 
