Chemical and Physical Notes 65 



to the following interesting connection between the freezing 

 and the boiling of saline solutions. 



The temperature of a saline solution at its freezing-point 

 is raised by melting ice in it, and the rate at which it raises the 

 temperature of the solution is the less the greater the amount 

 of ice melted. The more nearly the temperature of the 

 solution approaches to o C., the greater is the amount of ice 

 which must be melted in order to produce a certain rise of 

 temperature. When the temperature of the solution is ever 

 so little below o C., the amount of ice which has to be melted 

 in order to produce the smallest rise of temperature is ever so 

 great. But the temperature at which ice melts in a solution 

 is the temperature at which the solution freezes. Therefore, 

 for solutions containing the same amount of a salt, the 

 depression of the freezing-point is the less the greater the 

 amount of water present. In some cases the depression of 

 the freezing-point is exactly proportional to the reciprocal of 

 the amount of water present ; in other cases it deviates 

 slightly from exact proportionality in one sense or in the 

 other. 



The temperature of a solution at its boiling-point is 

 lowered by condensing steam in it ; and the rate at which 

 it lowers the temperature of the solution is the less the 

 greater the amount of steam condensed. The more nearly 

 the temperature of the solution approaches the temperature 

 at which saturated steam condenses on pure water, the 

 greater is the amount of steam which must be condensed 

 in order to produce a certain fall of temperature. When the 

 temperature of the solution is ever so little above the boiling- 

 point of pure water, the amount of steam which has to be 

 condensed in order to produce the smallest fall of temperature 

 is ever so great. But the temperature at which steam con- 

 denses in a solution is the temperature at which the solution 

 boils. Therefore, for solutions containing the same amount 

 of a salt, the elevation of the boiling-point is the less the greater 

 the amount of water present. In some cases the elevation of 

 the boiling-point is exactly proportional to the reciprocal of 

 the quantity of water present ; in other cases it deviates 



B. 5 



