Testing Milk and Its Products. 



94. Use of a 5 cc. pipette. When the cream is in good con- 

 dition for sampling, satisfactory results can also be obtained by 

 the use of a 5 jc. pipette, provided great care is taken in mix- 

 ing the cream before sampling; 5 cc. of cream are measured into 

 a milk test bottle, and two pipettefuls of water are added. In 

 this way all the cream in the pipette is easily rinsed into the 



test bottle. The readings multiplied by --=3.6 will give the 

 per cent, of fat in the cream. If the specific gravity of the 

 cream tested varies appreciably from 1, corrections should be 

 made accordingly; e. g., if the specific gravity is 1.02, the fac- 

 tor should read -^~~ r =3.53; if '95, -^y =3.79, etc. 



95. Proper readings of cream tests. The accom- 

 panying illustration (fig. 36), shows the proper method 



of reading the fat column in cream 

 tests; readings are taken from a to c, 

 not to & or to d, when readings are 

 made at 140 F. 1 



No special precautions other than 

 those required in testing milk have been 

 found necessary in testing cream, ex- 

 cept that it is sometimes advisable not 

 to whirl the test bottles in the centri- 

 fuge at once after mixing, but to let the 

 cream-acid mixture stand for a while, 

 until it turns dark colored. At first, 

 the mixture of cream and acid is much 

 lighter colored than that of milk and 

 FIG 36. Measur- acid, owing to the smaller proportion of 

 in g the e n a eck COl o U f m S solids not fat contained in the cream. 



m e a a d d e The liquid beneath the fat in a com- 



from a to c, not to i . -i , < n 



6 or to d. pleted test of cream is sometimes milky 



1 The size of the meniscus Is magnified in this cut. A study of the 

 mensicus formed in bottles with narrow or wide necks, and its bearing 



