228 Milk Inspection. 



10 c. c., for measuring the sulphuric acid, an 11 c. c. pipette for 

 milk and a 1 c. c. pipette or a corresponding automatic measure 

 for amyl alcohol. 



4. Commercial sulphuric acid of a specific gravity of 1,820 

 to 1,825 (at 15 C.). 



5. Amyl alcohol with a specific gravity of about 0.815 (at 

 15 C.) and a boiling point of 128 to 130 C. 



6. Shaking apparatus with a protective cover. 



7. Water bath. 



First sulphuric acid (10 c. c.) is poured into the butyrometer, 

 then 11 c. c. of milk, and finally 1 c. c. of amyl alcohol. The tube 

 is closed with a rubber stopper and then roughly shaken. Through 

 mixing, the contents become greatly heated. After the disappear- 

 ance of all flakes and after the tube has been held for several 

 minutes at 65 C., it is centrifugalized. Following the centrifu- 

 galization it is again heated at 65 C. and then quickly read. 



In order to avoid the more or less dangerous handling of 

 sulphuric acid, Sichler's "sinacid" and Gerber's "sal" methods 

 have recently been inaugurated, in which alkaline salt solutions 

 are employed instead of the sulphuric acid. The results are ap- 

 proximately the same as in the acid butyrometers. 



[In the United States the most popular method for determin- 

 ing the amount of fat in milk is by the Babcock test. If carefully 

 applied the results can be relied upon without question. 



In the application of this test sulphuric acid is used to free 

 the fat globules by dissolving the casein. Then by proper cen- 

 trifuging the fat is collected in such a manner that it may be 

 readily measured. 



For the execution of the test special test bottles are provided. 

 A definite amount of milk (17.6 c. c.) is placed into a test-bottle 

 to which 17.5 c. c. of commercial sulphuric acid of a specific gravity 

 of 1.82 to 1.85 is added by means of a pipette, burette or other 

 measuring apparatus. The contents are then thoroughly and 

 carefully mixed, as a result of which the fluid turns brown and 

 becomes somewhat heated. The bottles are then placed into a 

 centrifuge which is specially constructed for this purpose, and 

 centrifuged for 5 minutes at 900 to 1,200 revolutions per minute. 

 After removing the bottles from the centrifuge they are filled with 

 hot water up to the lower part of the neck and they are again 

 centrifuged for two minutes. A sufficient amount of hot water 

 is now added to float the melted fat into the neck of the bottle 

 which is provided with a graduated scale, and the centrifuging 

 is repeated for one minute. The volume of fat can be easily read 

 from the graduated portion of the bottle, and this reading should 

 be done while the neck of the bottle is still hot. Trans.] 



The fat content of the milk fluctuates between wide limits. 

 The total solids and the fat-free solids may be established with 



