153 



Fig. 18. Freezing curve of a solution under ideal conditions. Abscissae: 

 time; ordinates: temperature. 



a new delay results in the rate of cooling and the solution 

 becomes again more concentrated. The curve slowly fol- 

 lows a downward path BC. 



Such a curve is of the hyperbolic type, as is shown by 

 the following considerations. A 0.01 weight-molar (molal) 

 solution begins to freeze at - 0.0186°. To lower the freez- 

 ing temperature by a further 0.0186 degree, that is, to bring 

 the freezing point to - 0.0372°, the concentration should be 

 doubled; for another lowering of the freezing point by 

 0.0186 degree the concentration should be tripled, and so 

 on. To double, treble, etc. a weight-molar concentration, 

 the weight of water in the solution should be reduced 

 respectively to ^, h h etc., its original value. To reduce 

 the weight of water to h one should crystallize ^l of it ; to 



