178 THE FREEZING POINT OF MILK. 



The position on the thermometer scale of the freezing 

 point of water is determined in exactly the same way as 

 in the case of milk, distilled water being first placed in one 

 of the tubes " F/' and cooled in a mixture of ice and water. 

 Particular care, however, must be taken to break up the 

 ice formed and to prevent the formation of a shell of ice 

 round the sides and bottom of the tube. The fine ice should 

 extend from the surface to the bottom of the thermometer 

 bulb to ensure a good reading. It is much easier to deter- 

 mine the freezing point of a milk than that of water, owing to 

 the fact that " milk " crystals are easily kept small, while 

 water always tends to freeze in one lump. *l'he ditference 

 between the freezing i)oint of the distilled water and that 

 of the milk on the thermometer, gives the freezing point 

 of the milk. 



For deducmg the proportion of added water from the 

 determined freezing point, the following table, extended from 

 Winters, is used. 



