THE BABCOCK TEST 31 



5. Use nothing but clean, soft water in filling the 

 bottles. 



6. Be sure the tester does not jar. 



7. Be sure the acid is of the right strength. 



8. Mix as soon as acid is added to milk. 



9. Do not allow the bottles to become cold before 

 reading the test. 



10. Read the test twice to insure a correct reading. 

 The water added to the test bottles after they have been 



whirled should be clean and pure. Water containing 

 much lime seriously affects the test. Such water may 

 be used, however, when first treated with a few drops of 

 sulphuric acid. 



As stated before skim-milk, buttermilk, and cream are 

 tested in the same way as milk, with the exception that 

 the cream sample is weighed not measured. 



Cleaning Test Bottles. As soon as the test is read, 

 the bottles are emptied by shaking them up and down so 

 as to remove the white sediment. Next wash them in 

 hot water containing some alkali, and finally rinse them 

 with hot water. Occasionally the bottles should be rinsed 

 with a special cleaning solution, which is made by dis- 

 solving about one ounce of potassium bichromate in one 

 pint of sulphuric acid. A small brush should also oc- 

 casionally be run up and down the neck of the bottle. 



Testing or Calibrating Milk Bottles. Fill the bottle 

 to the zero mark with water, or preferably wood alco- 

 hol to which a little coloring matter has been added. 

 Immerse the lower section of the tester, shown in Fig. 12, 

 in the contents of the bottle. If the bottle is correct, the 

 contents will rise to the 5% mark. Next immerse both 

 sections of the tester which will bring the contents to 

 the 10% mark if the bottle is correctly calibrated. 



