tf WATER by HEAT. 401 



This experiment fpeaks in as decided language as the prece- 

 ding. It fliows that when a portion, in the middle of a column 

 of water at temperature 39.5 is cooled, the colder fluid rifes, and 

 does not defcend through the warmer mafs, and prefents tke 

 unequivocal demonftration, that water of temperature 39^° is 

 adually expanded by loiing heat. 



The different experiments which I have in detail recorded, 

 agree perfecftly with each other in the evidence they give relative 

 to the fubjecl of inquiry. The general import of them is, that 

 water which is ice-cold, or a few degrees warmer, when heated, 

 becomes fpecifically heavier, — that water of 40° when heated 

 becomes fpecifically lighter, — that water above 40', by the lofs 

 of heat, or by cold, is rendered fjpecifically heavier ; and that 

 water below 40° is, by the fame caufe, rendered fpecifically 

 lighter. 



Such being the general import, the conclufion is irrefiftible, 

 that heat, in low temperatures, caufes water to contract, and at 

 fuperior temperatures to expand. The opinion, therefore, is 

 founded in truth, that water poffeffes a peculiarity of conftitu- 

 tion in relation to the effedls of caloric, and that it is, within a 

 fhort range of temperature, an exception to the general law of 

 " expanfion by heat." 



So far as I can judge from thefe experiments, I am difpofed to 

 believe that the point at which the change in the conftltution of 

 this fluid in relation to heat takes place, lies between the 39t" 

 and the 40th degree. 



I AM not at prefent aware of any objedlion to the method I 

 have followed in eftablifliing this Angular anomaly, and in re- 

 moving any doubts which may have ariien from the unavoid- 

 able influence which the inflrument mufl have in the mode of 

 conducting the inveftigation that had previoufly been adopted. 



The plan of operation above defcribed, however, only af^ 

 certains the fadt ; it gives no data for afcertaining the amount of 

 the anomalous effedt of heat. 



3F 2 I 



