On the Contraction of Water hy Heat. \ 69 



rise of several degrees, before the surface indicates the 

 smallest acquisition of heat. 



The inference is plain, that the cold water is contracted 

 by the heat. 



The change of the effect of heat is equally well illustra- 

 ted by this experiment. 



No sooner did the inferior portion attaui the temperature 

 of 39", than the heated fluid altered its course, and, by 

 ascending, carried the increase of temperature very rapidly 

 to the surface, so that it soon surpassed the bottom, and 

 continued to rise, while the other remained stationary. 



Experiment VI. 



I filled thejarused in the last experiment with water of 

 tunpcrature 39^", the air and the support being at a*)". 

 Disposing the thermometers in the usual manner, I intro- 

 duci.^d a mixture of snow and salt into the bason. 



Bottom. Top. Air. 



At commencement 3\)-b syj 3y° 



In 10 minutes 39+ 38 + 



— 25 39+ 36-5 %* At this time ice 



• — 35 39 36 — began to be 



— 55 39 33 formed on the 



— an hour and 10 min. 39 — 34+ sideof the ves- 



•O J 



■39— 31— sel. 



— 2 hours 39— 33 + 



This experiment speaks in as decided language as the 

 preceding. It shows that when a portion, in tlie middle 

 of a column of water at temperature 39"3 is cooled, the 

 colder duid rises, and does not descend through the warmer 

 mass, and presents the unequivocal demonstration, that 

 water of temperature 39,}° is actually expanded by losing 

 heat. 



The different experiments \\hich I have in detail recorded, 

 agree perfectly with each other in the evidence they give 

 relative to the subject of inquiry. The general import of 

 them is, that water which is ice-cold, or a few degrees 

 warmer, when heated, becomes specilicallv heavier, — that 

 water of 40" when heated becomes speciticallv lighter, — 

 that water above 40", by llie loss of heat, or by cold, is 

 rendered specifically heavier; and that water below 40" 

 is, by the same cause, rendered speciliealiy lighter. 



Such being tlie general import, the conclusion is irre- 

 sistible, that lu:;!i, in low temperatures, causes water to 

 contract, and at superior tenjperalures to expand. Tlie 

 opinion, therefore, is founded ui truth, that water pos- 

 sesses 



