80 Chemistry. [Lecture 26. 



ether was first put in, it was about fifty-eight 

 degrees, but it became so cold when boiling, that 

 a quantity of water in a surrounding vessel was 

 suddenly frozen. The manner in which the 

 phasnomenon may be accounted for is this : the 

 weight of the atmosphere being removed, the 

 caloric the ether contained was sufficient to make 

 it boil. The heat that disappeared, or, in other 

 words, the cold that was produced, while the 

 ether was boiling, is easily accounted for. The 

 boiling of the ether, like the boiling of water, 

 arose from the conversion of the fluid into a va- 

 pour more subtile than itself; but the conversion 

 could not take place without the absorption of a 

 considerable quantity of caloric, that is, much 

 of the sensible heat of the fluid became latent in 

 vapour. Now it is well known that water and 

 spirit of wine boil in vacuo many degrees below 

 their boiling point under the pressure of the at- 

 mosphere. It is natural, therefore, for ether, 

 which boils in the open air, when heated to 

 about the heat of the human blood, to boil in 

 vacuo twenty-four degrees below 0, which is a 

 degree of cold sufficient to freeze any water that 

 may be in contact with the vessel which contains 

 the ether. 



This experiment ought to be attended to, be- 

 cause it is a clear proof that the sudden dimi- 

 nution of heat is not always occasioned by its 

 being taken away by the surrounding matter. 



This evaporation at low temperature is not 



