MILK INSPECTION 191 



■of acid, but if the pink coloration fades and disappears it shows 

 that the mixture contains more than this amount of acid and is 

 unfit for retailing, for pasteurizing, or for cheese or butter making. 

 A more exact method of using the tablets for testing the acidity of 

 cream may be done. This is very useful for the butter maker in 

 informing him of the progress of the ripening of cream, and also in 

 showing whether or no two lots or cream may be mixed safely, 

 and again it may be used to test the acidity of whey. When cream 

 contains 0.5 to 0.6% acidity, it is as sour as it should be for butter 

 making. Full directions for use of the Farrington alkaline tablets 

 are supplied with the tablets. 



A test by which the percentage of acidity of milk may be more 

 accurately determined than is necessary by the dairyman, is that 

 in which the alkali is lime water. 



To make lime water, used in testing the acidity of milk, we 

 may get from a grocery store an ounce or so of lime; add a pint 

 of water, and stir thoroughly. Allow the undissolved lime to 

 settle, and pour off the clean lime water, which will contain any 

 potassium or sodium that may have been present in the lime. Do 

 this several times. Now pour on a quantity of distilled water 

 depending on the sized bottle the lime water is kept in, and cork; 

 when the lime has settled so the water is clear, it is ready to be 

 used and may be removed as wanted with a pipette, as will be 

 described presently. Always have some undissolved lime at the 

 bottom of the jar, as by this means the lime water is readily kept 

 saturated. As fast as the lime water is used, add distilled water to 

 take its place. It is well to use a fresh lump of lime every two 

 or three months, as in time the sediment may consist of carbonate 

 of lime, owing to absorption of carbonic acid from the air. 



To test the acidity of milk * with lime water : ( 1 ) First mix 

 the milk thoroughly, and (2) with a graduated 1 c. c. pipette 

 (such as is shown in Fig 41) place 1 c. c. of the milk in a small 



* This test is taken from Chapin's Theory and Practice of Infant Feeding. 



