DETERMINATION OF FATS. 



41 



30 



10 



acidified with acetic acid and shaken with lo 

 c. c. of ether. Then adding lo c. c. of alcohol 

 (96 per cent), the tube is placed in a water 

 bath at 40 degrees and allowed to remain for 

 a short time. The fats dissolve in the ether 

 and collect on the surface. On the graduated 

 scale, the length of the layer of fat solution is 

 read off, and from this figure the percentage 

 of fats in the sample is determined from the 

 tables which accompany the apparatus. In 

 large dairies and creameries a similar method 

 for fat estimations- is used almost exclusively. 

 A measured quantity of the milk is treated 

 with a special acid solution, acetic acid or 

 sulphuric acid (for Laval's lactocrite) in a 

 graduated tube, which is placed in a centrifu- 

 gal machine and revolved at the rate of six 

 thousand to seven thousand turns per minute. 

 By this means the fat separates out as a clear 

 compact layer. According to Laval, Ger- 

 ber, Demichel, Rose - Gottlieb, and oth- 

 ers, these processes, making use of centrifugal force, give 

 results that are very useful in commercial practice. They 

 are especially well adapted to work in large creameries 

 because a large number of tests may be made in a short 

 time.* 



Fig. 6. 



The 

 Marchand- 



ToUeas 

 Lactobuty- 



rometer. 



''"The Babcock Method. — One of the most expeditious methods 

 for ascertaining the percentage of fats in milk is the so-called 

 Babcock test. It is a simplified modification of the lactocrite 

 method described above. The results obtained by the process are 

 very satisfactory, and usually accord well with the results of 

 ether extractions. 



In brief the method consists in measuring out, by means of a 

 special pipette. 17.6 c. c. of the milk sample and transferring to 

 a graduated Babcock flask. To this is added 17.5 c. c. of strong 

 sulphuric acid (sp. gr. 1,81 — 1.83). The milk and acid are thor- 

 oughly mixed by gently rotating the flask. By this treatment the 

 casein dissolves completely forming a dark brown fluid, and the 



