EXPERIMENT STATION BULLETINS. 



337 



dividers. These are then removed and one point is placed at the zero 

 mark on the scale of the bottle used, the other point will indicate the 

 exact per cent of the fat in the milk tested. 



TESTING CREAM. 



The principal point of difference in testing cream and whole milk is 

 that the cream is always weighed. Cream cannot be measured in a pipette 

 for the following reasons : — 



1. It is lighter than milk because it contains a higher per cent of 

 fat which is the lightest constituent of milk and because of its viscosity 

 it oftentimes holds large numbers of air bubbles, hence 17.5 cc. of 

 cream would not weigh 18 grams. 



2. Cream being viscous, a considerable quantity adheres to the side of 

 the pipette. 



Operating the Test. — 



1. The cream is first thoroughly mixed. 



2. The required sample is then weighed out. In case of a rich cream 

 where a bottle graduated from 0-30% is used, a half sample or 9 grams 

 is taken. If the bottle is graduated from 0-50% an 18 gram sample is 

 used. 



3. In case of a 9 gram sample, add one-half pipette of water but do 

 not add any to the 18 gram sample. 



4. In both cases, add 17.5 cc. of acid and proceed as with whole milk 

 test. 



Reading the Percentage of Fat in the Cream Test. — ■ 



In the cream as well as in the whole milk test bottle, there is a marked 

 concavity in the upper surface of the fat column while the lower ex- 

 tremity is nearly a straight line. In reading the fat column, the length 

 is measured from the bottom line to a point half way between the upper 

 and lower line of the concavity in the upper surface. See ill. 6. The 





i=-20 



r^:^ 



r^ 



Illustration 6. 



whole concave space -is not allowed because of the large bore of the 

 neck of the cream bottle. 



When a 9 gram sample is used, multiply the resulting test by two. 

 43 . ' 



