EVAPORATED MILK STRIKING 121 



should be sensitive and its scale should be subdivided into tenth 

 degrees. The batch should be " struck" at a uniform tempera- 

 ture, say 120 degrees F., so as to avoid misleading readings of 

 the hydrometer. A difference of a few tenths degrees Beaume 

 affects the behavior of the evaporated milk in the sterilizer very 

 appreciably. If the density is too great the product may badly 

 curdle during sterilization. If the density is too low the evapor- 

 ated milk may be below the legal standard. It is advisable for 

 the operator to use a pail of water of the proper temperature, 

 when he strikes the batch, so that he can adjust the temperature 

 of the milk in the hydrometer jar readily and quickly, and need 

 not depend entirely on the temperature of the milk in the pan 

 which may change several degrees while he is engaged in the 

 operation of striking. The hydrometer jar containing the sample 

 of evaporated milk is set into the pail of hot water of the desired 

 temperature, the hydrometer is inserted in the jar and the read- 

 ing is taken. 



While the Beaume hydrometers should be used at the tem- 

 perature for which they are graduated, which is 60 degrees F., 

 they answer all practical purposes at any other temperature : 

 at 120 degrees F. for instance. The chief essential is to take the 

 reading at some uniform and definite temperature and read the 

 Beaume at that same temperature in the case of every batch. In 

 that way the results are comparable. The operator soon learns, 

 that at a given temperature the evaporated milk of proper den- 

 sity shows a certain Beaume reading. When the reading is 

 higher or lower, the milk has either been condensed too much or 

 not enough. The use of the automatic "striker" described under 

 ''Striking S\veetened Condensed Milk," practically solves the 

 control of the temperature of the sample taken. 



The same formula, however, cannot be used under all con- 

 ditions. No rule-of-thumb method of determining the density 

 can therefore be established. Aside from the degree of conden- 

 sation, the specific gravity of the milk varies with locality, season 

 of year, quality of milk, etc. This means that what is the proper 

 Beaume reading in o'ne locality, or at one season in the same 

 locality, may be entirely wrong in another locality, or at other 

 seasons in the same locality. If uniformity in the density and 

 behavior of the batches of evaporated milk is to be secured 



