318 



EBULLITION. 



considerably increased, the solar heat would undergo a corresponding diminu- 

 tion, and many of the substances which now assume the liquid form would 

 then become solid. The sea which surrounds the globe would take the form 

 of a mass of solid crystal. Substances now in the gaseous state might be re- 

 duced to the form of a liquid ; nay, that the atmosphere should be converted 

 into a sea by a sufficient diminution of temperature, is an effect not only within 

 the bounds of possibility, but probable upon the clearest and best-founded 

 analogy. 



In reviewing what has been stated in the present discourse, it will be per- 

 ceived that the following general facts have been established, which form the 

 basis of all investigations concerning the phenomena of the conversion of 

 liquids into vapor by ebullition : 



1. A liquid, when raised to a certain temperature, boils, and is converted 

 into vapor. The boiling point of a liquid varies with the pressure to which it 

 is submitted : the greater this pressure, the greater will be the temperature at 

 which the liquid boils. 



2. During the process of ebullition no increase of temperature takes place, 

 though a considerable portion of heat is imparted to the boiling liquid. 



3. Different liquids undergo the process of ebullition under the same pres- 

 sure at different temperatures ; and the temperature at which a liquid boils under 

 the medium pressure of the atmosphere, or thirty inches of mercury, is called 

 its boiling point. 



4. Different liquids absorb different quantities of heat in the process of 

 ebullition. 



5. The elastic force of the vapor into which a liquid is converted is equal 

 to the pressure under which the liquid boils. 



6. The states of liquid or vapor are not essentially connected with the na- 

 ture of bodies, but are merely accidental on the temperature to which bodies 

 are exposed, nor does a body change its nature or essential properties in passing 

 from the one state to the other. 



