TESTING FOR BUTTERFAT 629 



the bulb terminates into a threaded neck into which fits a rubber 

 stopper. 



2. Butyrometer stand and water bath. 



3. 1.1 cc. pipette for milk. 



4. 3 cc. pipette for cream. 



5. 10 cc. pipette graduated to .l.cc. 



6. 8.2 cc. pipette for diluting cream. 



7. 10 cc. bulb pipette for acid, or automatic acid measuring 

 apparatus. 



8. 1 cc. pipette for amyl alcohol. 



9. Centrifuge. 



Commercial sulphuric acid, specific gravity 1.82 to 1.825 at 

 15 C. (59 F.). 



Pure amyl alcohol, specific gravity .8165 to .818 at 15 C. (59 F.) 

 boiling point 124-130 C., should give a clear solution with an equal 

 volume of strong hydrochloric acid. 



Operation of Test 



Milk, Skim Milk, Buttermilk, Whey. Place the butyrometers 

 in rack or stand. Add 10 c.c. sulphuric acid to each, measure 11 c.c. 

 of properly mixed sample of milk and then 1 cc.'of amyl alcohol 

 into the butyrometers. 



Insert corks, place thumb over cork and shake until all the curd 

 is dissolved. Completely invert the stand several times to insure 

 thorough mixing. 



Place the butyrometers into the centrifuge with corks toward the 

 periphery, and whirl two to three minutes, or until the fat column 

 is perfectly clear. 



Place butyrometers into water bath at 60 to 70 C. (140-158 F.) 

 and read. So adjust the rubber stopper in the bottom of the bulb 

 while reading, that the bottom of the fat column coincides with, the 

 zero graduation. Read to the bottom of the meniscus. Compara- 

 tive tests have demonstrated that this test yields very accurate 

 results. 



Skim milk and buttermilk should be whirled longer and at maxi- 

 mum attainable speed and .05 per cent must be added to the reading. 1 



Cream. Wyssmann and Peter 2 recommend dilution of the 

 cream at the rate of one part of cream to four parts of water, mak- 



1 Richmond, Dairy Chemistry, 1914. 

 2 Wyssman und Peter, Milchwirtschaft, 1907. 



