Sampling Milk. 27 



allowed to stand for a while, with frequent stirring, until 

 the curd is all dissolved and an even translucent liquid 

 is obtained. Such milk may become dark-colored by 

 the action of the alkali, but this color does not interfere 

 with the accuracy of the test. 



Instead of powdered soda or potash, these substances 

 dissolved in water (soda or potash lye), or strong am- 

 monia water, may be used for the purpose of dissolving 

 the coagulated casein in a sample of sour milk. In this 

 case, a definite proportion of alkali solution must, how- 

 ever, be taken, 5 per cent, of the volume of milk being 

 usually sufficient, and the results obtained are increased 

 accordingly. (See example cited on p. 25.) 



33. Sampling frozen milk. When milk freezes, it sep- 

 arates into two distinct portions: Milk crystals, largely 

 made up of water, with a small admixture of fat and 

 other solids, and a liquid portion, containing nearly all 

 the solids of the milk. In sampling frozen milk it is 

 therefore essential that both the liquid and the frozen 

 part be warmed and mixed thoroughly by pouring gently 

 back and forth from one vessel into another; the sample 

 is then taken and the test proceeded with in the ordinary 

 manner (36). 



