Condensed Milk and Milk Powder 67 



servant operator knows within a few minutes, when the milk is con- 

 densed enough. This does not mean, however, that he should wait 

 until the last minute before he "strikes" the batch, for even the most 

 skillful and experienced processors are easily deceived by the mere 

 appearance of the condensed milk through the eye-glass. 



The degree of concentration may be more accurately determined 

 by taking a sample from the pan and testing it by various methods, 

 such as by weighing a definite quantity of condensed milk on a sen- 

 sitive scale, by the use of a resistance apparatus, or by the use of a 

 specially constructed hydrometer. Of these the Beaume hydrom- 

 eter has been found the most suitable to use. 



Mechanical devices and methods, such as the above, can be 

 depended on, when all the conditions influencing the specific gravity 

 of the liquid are under control, and when there is plenty of time 

 for their manipulation. When the boiling and rapidly evaporating 

 milk in the retort is approaching the proper density, however, quick 

 action is essential. One minute over or under condensing, may cause 

 the milk to be either too thick or too thin for the market and may 

 necessitate the "re-running" of the entire batch. These instruments 

 are, therefore, practically worthless at the time they are needed 

 most. There is not time to carefully measure and weigh out a sam- 

 ple of sweetened condensed milk, nor can the processor always wait 

 until the hydrometer has found its equilibrium in as viscous a fluid 

 as sweetened condensed milk. Again, the density or specific grav- 

 ity of the finished product depends, outside of the degree of con- 

 centration, on many and fluctuating conditions, such as amount of 

 heat applied toward the end of the process, the temperature of the 

 sample when drawn, and the per cent, of fat and cane sugar in the 

 condensed milk. It is for these reasons that arbitrary mechanical 

 instruments and "methods are not uniformly satisfactory, and are 

 prone to yield misleading results. The experienced eye and good 

 judgment of the processor are all essential. The following are sat- 

 isfactory and reliable methods of "striking," which, with a little 

 experience, enable the operator to determine the proper degree of 

 condensation : 



Draw a sample from the pan into a tin dipper, lower the dipper 

 into a pail of ice water or snow. Stir the condensed milk with a 

 metal-back thermometer until the condensed milk is cooled to 70 



