20 A DAIRY LABORATORY GUIDE 



EXERCISE IV 

 BABCOCK TEST 



1. Test by the Babcock method a sample of whole 



milk, skimmed milk and butter. 

 Mix the butter properly before weighing it out 

 for the test. 



2. Measure out about 2^ grams of skimmed milk 



(Babcock pipette twice full to the mark). 

 Divide approximately into four parts. Test 

 two of these parts for boiling by two dif- 

 ferent methods. Boil the remaining i8 

 grams, divide approximately into two parts 

 and test for boiling by two different methods. 

 Give the chemicals used in each case. Do 

 not add the chemicals to the milk while the 

 milk is hot. 



3. Measure out in duplicate a sample of skimmea 



milk as for the Babcock test. Before adding 

 the sulphuric acid dip your stirring rod into 

 the formaldehyde and rinse it off in one of 

 the samples. Then add to both samples the 

 ferric chloride and sulphuric acid and note 

 the difference in color due to formaldehyde. 



4. Test for formaldehyde any four of the samples 



furnished. Report the results by number. 

 Sometimes sulphuric acid will alone give the 



■color test for formaldehyde. Why is this? 

 Why is it best to always add the ferric chloride 



when making the formaldehyde test? 



