86 



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 t!c. 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 -'-^—=3.53; if .95, ^^-=3.79, etc. 



5X1.02 ' ' 5X.95 ' 



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 b or to d, when readings are 

 made at 140° F.* 



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, 

 ot — h-^B^ the mixture of cream and acid is much 

 lighter colored than that of milk and 

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

 In the^ neck^of^a solids not fat Contained in the cream. 



cream bottle. Read- „, ,. . j i .■> .^ i. i • 



ing should be made ihe liquid beneath the fat m a com- 



trom a to c, not to , , j , . « . . , . .,, 



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



» 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 



-30 

 -28 

 -26 



-24- 



3— 22 

 5—20 

 E — IB 

 E—IB 

 z — 14 

 zr— 12 

 ^10 



-flC 



