66 MAINE AGRICULTURAL EXPERIMENT STATION. 



MAKING THE TEST. 



Mixing the Sample. Even- precaution should be taken to 

 have the sample represent the milk or cream from which it is 

 taken. Milk fresh from the cow can be thoroughly mixed by 

 pouring three or four times from one vessel to another, but milk 

 or cream that has stood until a layer of thick cream has formed 

 on the top must be mixed until the thick cream is broken up and 

 the whole mass appears homogeneous. No clots of cream 

 should appear on the surface when the sample is left quiet for a 

 moment. The mixing should not be too violent or carried to 

 excess, for in this way little granules of butter may be separated 

 or the sample filled with air bubbles, making it impossible to 

 measure out the required quantity. 



Large quantities of sour milk or cream cannot be sampled, 

 but small lots of a pint or quart can be put in proper condition 

 by the following treatment: Add to the sample powdered "con- 

 centrated lye" or caustic soda, (a small thimbleful to a pint of 

 milk or cream is sufficient,) heat in a closed jar or bottle in water 

 to about i io" to 120"" F.. shake thoroughly, and allow to cool to 

 about jo z F.j when it will be found to be in as good condition 

 to measure as when fresh. 



Measuring the sample for a test. When the sample has been 

 sufficiently mixed, fill the pipette by placing its lower end in 

 the sample and sucking at the upper end until the milk or cream 

 rises above the mark on the stem; then remove the pipette from 

 the mouth, and quickly close the tube at the upper end by firmly 

 pressing the end of the index finger upon it to prevent access of 

 air. So long as this is done the sample cannot flow from the 

 pipette. Holding the pipette in a perpendicular position, with 

 the mark on a level with the eye, carefully relieve the pressure 

 on the finger so as to admit air slowly to the space above the 

 liquid. In order to more easily control the access of the air, 

 both the finger and the end of the pipette should be dry. When 

 the upper surface of the liquid coincides with the mark upon the 

 stem, the pressure should be renewed to stop the flow. 



Next, place the point of the pipette in the mouth of one of 

 the test bottles, held in a slightly inclined position so that the 

 liquid will flow down the side of the tube, leaving a space for the 



