— 145 — 



obtained, and in case the skim-milk or buttermilk is acid, which 

 so frequently occurs, the amount of paper extract will even equal 

 or exceed the weight of fat present. The paper method cannot 

 be used with satisfaction or safety on skim-milk or buttermilk, 

 while the ignited asbestos can be. 



3. COMPARISON OF RESULTS BY DR. S. M. BABCOCK'S CEN- 

 TRIFUGAL METHOD FOR THE DETERMINATION OF FAT 

 IN MILK AND THE GRAVIMETRIC METHOD. 



« 



Dr. Babcock's new method for the determination of fat in milk 

 with the aid of a small centrifugal machine. has been compared 

 with the gravimetric method. The figures given in each column 

 of the following Table are averages of duplicate determinations, 

 and include results on the milk from individual cows, as well as 

 from the mixed herd. 



KIND OF SAMPLE. 



Fats by 

 gravi- 

 metric. 



Fats by 

 centri- 

 fugal. 



Skim milk, . . 

 Skim milk, . . 

 Whole milk,. . 

 Whole milk,. . 

 Skim milk, . . 

 Skim milk, . . 

 Whole milk,. . 

 Whole milk,. . 

 Watered milk, 

 Watered milk, 

 Skim milk, . . 

 Skim milk, . . 

 Skim milk, . . 

 Skim milk, . . 

 Whole milk,. . 

 ? 



.60 



•47 

 3 9° 

 4.16 



•5i 

 .72 



4-53 



4.27 



2.00 



2.31 



.68 



i-54 



•49 

 .76 



5.22 



[.84 



1. 28 



•50 



•5o 



3-90 



4. 10 



•50 

 .68 



4-45 

 4-23 

 2.00 

 2.50 



•73 



1.50 



.60 



•73 

 5-35 

 1. So 

 1.30 



NOTES. 



No hot water used in centrifugal 



< ( t l << 4 < 



(( 



it- 



Samples kept 24 hours after 

 measuring before fats deter- 

 mined. 



Samples kept 36 hours after 

 measuring before fats deter- 

 mined. 



For the use of dairymen, this is the most rapid and accurate 

 method which has yet been tested in this laboratory. The appa- 

 ratus is not expensive ; besides the centrifugal it consists simply 

 of a number of test bottles, similar in shape to those used in 

 Short's method, a measure for the milk, and one for the acid. 

 Equal volumes of milk and concentrated sulphuric acid are mixed 

 together in the test bottles, and then whirled in the centrifugal for 

 five minutes, at the rate of nine hundred revolutions per minute. 



