110 A A T cw Dairy Industry. 



Besides the fat test, it becomes necessary, periodi- 

 cally, to make a test of the acidity of the milk to be 

 used ; this is more particularly the case in hot weather, 

 or where ensilage is fed, or any apprehension exists 

 as to the sweetness of the fodder or pasturage. For 

 the acid test, 50 cub. cent, of milk are placed in a 

 glash dish, 2 CC of hydrate of sodium and two or three 

 drops of phenolphtalein added and mixed together. 

 To this we now cautiously add common sulphuric 

 acid, by means of a graduated pipette, constantly 

 stirring, until a decidedly pink tinge appears in the 

 milk. When this has set in the accurate quantity of 

 acid added in c. c. is ascertained, and we call every 

 cubic centimeter added one degree of acidity. In 

 this way milk to be used in the manufacture of nor- 

 mal milk may contain no more than three degrees of 

 acidity, any excess of this quantity will tend to spoil 

 the milk to make it curdle. Milk that shows 4.5 

 degrees of acidity is unfit for the manufacture of 

 normal milk. Milk which has turned sour shows 

 2G.5 degrees of acidity ; butter may show 15 degrees. 



If w r e have found our milk sweet we now 7 proceed 

 to the separation of the cream from the skim milk, 

 conducting the milk into a tempering vat where it 

 attains a temperature of 80 F. The separator is 

 graduated in a manner to tiirn out one-third of the 

 volume of the milk as cream and two-thirds as skim 

 milk. This must strictly be adhered to, as on this 

 division all subsequent calculations are based. After 

 the separator gets first started, .four or five gallons of 



