16 



make it possible for him to turn out more uniform products, but it will 

 also enable him to act with confidence and more intelligently to pursue 

 the work he may have on hand. 



MILK AND CREAM TESTING. 

 By J. A. McFeeters. 



Normal milk may be considered as an emulsion. The chief constitu- 

 ents are fat, casein, sugar, albumen, a small amount of mineral matter — 

 ash, together with a large percentage of water. 



As fat is the most variable of the milk constituents the ability to ac- 

 curately determine the percentage present is an essential qualification 

 for a successful dairyman. 



The importance of this becomes at once apparent under conditions 

 where the commercial value of milk is in direct proportion to its fat 

 content. A means of detecting mechanical losses, due to faulty methods 

 in the course of manufacture, adulterations by the producer or dealer, or 

 of testing the real worth of the different members of the dairy herd, is 

 of inestimable value to a dairyman. 



The details connected with an accurate, speedy fat determination of 

 a normal sample of milk, by means of the Babcock test, are briefly as 

 fellows : 



1. After thoroughly mixing, preferably by pouring from one vessel 

 to another, a representative sample should be taken. Too great care can- 

 not be exercised at this step. A test is of no value whatever if this point 

 be overlooked. 



2. By means of a 17.6 cubic centimeter (c.c.) pipette, take 18 

 grams of milk at a temperature of from 60 to 70 degrees. 



3. Add to this 17.5 c.c. of commercial sulphuric acid with a speci- 

 fic gravity (sp. gr.) of 1.82 to 1.83, and thoroughly mix the acid and 

 milk by giving the bottles a gentle rotary motion. 



4. Place the bottles in the tester and whirl for from four to five 

 minutes, at a speed varying from 700 to 1,200 revolutions per minute, 

 according to the diameter of the machine (700 revolutions per minute 

 with a machine twenty inches in diameter). 



5. Add hot water at a temperature not lower than 140 degrees 

 F. to float the fat into the neck of the bottle. 



6. Rotate the machine again for about two minutes and take the 

 readings before the fat cools. If troubled with burnt readings, add 

 the water twice instead of all at once, filling the bottle iust to the neck 

 the first time, then turn the machine about a minute, fill to about the 

 eight per cent, mark the second time, and whirl for another minute. 



7. Read the fat column at a temperature of from 120 to 140 de- 

 grees F. 



