160 NEUTRALIZATION OF SOUR CREAM 



The following concrete example of neutralization may serve 

 to illustrate this more clearly: The vat contains 2000 pounds of 

 cream, the cream tests .6 per cent acid, which is to be re- 

 duced to .25 per cent acid. How many pints of lime mix must 

 be added? 



Answer : . 



Original acid in cream 6 % 



Acid desired 25% 



Acid to be neutralized 35% 



Hence the amount of lime mix 



required is .35 X 2000 X .01644 = 11.5 pints. 



On the basis of this formula, then, the amount of lime mix 

 required to reduce any per cent of acid in any amount of cream 

 to the desired per cent acid, can readily be calculated, and 

 tables can be assembled whereby the exact amount of lime mix 

 needed can be read off at a glance. For the convenience of the 

 operator tables on pp. 158 and 159 are shown. 



If the creamery prefers to make up its milk of lime direct 

 from lime oxide or quick lime, which is unslaked lime, the 

 same formula and the same tables may serve without interfer- 

 ing with their accuracy, provided that the formula used for 

 making up the milk of lime is modified. The unslaked lime 

 or lime oxide is stronger than the hydrated lime, hence the milk 

 of lime used must contain somewhat less lime. The molecular 

 weight of lime oxide is 56, while that of lime hydrate is 74. 

 Hence instead of using enough lime to make each gallon of 

 milk of lime contain two pounds of lime, the amount of lime oxide 

 per gallon of milk of lime must be 74 : 56 = 2 : X; X = 1.5135 

 pounds lime oxide. 



Accuracy of Results of Neutralization Depends on Kind of 

 Lime Used. The foregoing calculations were made on the 

 assumption that the hydrated lime used contains 100 per cent 

 calcium hydrate or nearly so, and examinations of the hydrated 

 calcium limes of commerce have shown, that many of these limes 

 approach this standard of purity quite closely, so that the above 

 calculations should yield the acid reduction herein indicated. 



