Contents xiii 



PAGE 



boiling temperature of solutions of different strengths below 



that of saturation . -151 



If a solution can condense steam from the outside, it 

 necessarily must be able to condense its own steam, because 

 the two substances are identical. Therefore, steam intro- 

 duced from the outside must continue to raise the temperature 

 of the solution even after it has passed above the temperature 

 of the boiling water from which it has been obtained and 

 until the temperature of the solution has been raised to that 

 at which the solution itself liberates steam of atmospheric 

 pressure, and, by consequence, allows steam of atmospheric 

 'pressure introduced from the outside to pass freely through 

 it. It follows further that, to determine the boiling point of a 

 saline solution, it suffices to pass a current of steam of atmo- 

 spheric pressure through it until it raises the temperature of 

 the solution to a maximum, and that is the boiling-point of 

 the resultant solution. 



The following law holds : The temperature at which steam 

 condenses depends on the nature of the medium in which it 

 condenses ; and the temperature at which it is generated 

 depends on the medium in which it is generated ; and the 

 temperature at which steam condenses in a given medium is 

 that at which it is generated in the same medium ; the pressure 

 in all cases remaining uniform. 



The above method of determining the boiling-points of 

 saline solutions gives, easily, results of the greatest precision. 

 When the solution is boiled over a flame the results are 



irregular and untrustworthy 152 



Preliminary remarks on the experiments to be made, and 

 examples of the solubilities of some salts at the boiling 

 temperatures of their saturated solutions . . . 154 



Apparatus and method of experimenting . . . 155 



The result to be obtained from each experiment is the 

 difference between the temperature of pure saturated steam 

 and the maximum temperature produced by the condensation 

 of such steam in the brine, or the mixture of salt and brine. 

 Therefore, the temperature of pure saturated steam must be 

 observed at the same time as that of the boiling brine. It 

 follows that for the conduct of these experiments observation 

 of the barometer is unnecessary ... . . 158 



Importance of the relative dimensions of the entry and 

 exit of the steam-tube : experiment which proves the efficiency 



of the steam-tubes used '59 



It is essential that the thermometer and the inside of the 



