Oil Ike. Contraction of IVater hy Heat, 163 



Bottom. Top, 

 In 21 minutes 44 — 46-— 



— 31 4 2 44 



— 41 41 42 



rAt this time a thin fihn of 

 ■ — 51 40" + 34 < ice be<:an to form in contact 



(.with the crlass. 



34 



(A crust of ice of some thick- 

 ness now hned the glass. 



(.and air had fallen to 40°. 



— 5X 39 



— 11 



atm 



• 1 '-^'w f 39 Cfust of ice complete, 



idnigitj ^ ^ 



— 19- j^.-e-Ug Air 40". 

 next morning J 



P Air 40". So much ice had 



— 26 40- J melted that the cake was 



— 32 40 { detached from the side of 



i^the vessel, and tloated. 



— 41 40 Air 41". Ice not all melted. 



— 50 41 Air42'\ Ice not entirely gone. 



This long protracted experiment presents some striking 

 facts, and its general import, with regard to the subject of 

 investigation, agrees with the preceding. In it we see, 

 that when the frigorific mixture abstracted caloric from the 

 upper extremity of a cylinder of water, nearly 18 inches 

 long, and at 50", the reduction of temperature appeared 

 ^oonc^, and advanced quicker at its lower extremity than 

 in the axis at the top, not two and a half inches distant 

 from the cooling power. No one can entertain a doubt 

 that this is owing to a current of cooled and condensed 

 fluid descending, and a corresponding one of a warmer 

 temperature ascending. Now, if waterobserved the same law 

 that other bodies do, and had no peculiarity of constitution, 

 the same progress of cooling should continue. This, 

 however, the experiment teaches us, is not the case: as 

 soon as the fluid at the bottom exhibits a temperature of 

 40", it ceases. Ti)c colder fluid remains at top, and, quick- 

 ly losing temperature, ere long begins to freeze. The con- 

 tinuance of the colder fluid at the surface surely denotes, 

 that it is not more dense than the subjacent warmer water. 

 The legitimate inference from this is, that water of tem- 

 perature 40" is not contracted by biiuig cooled to 32°. 



L 2 Did 



