ON MILK AND MILK-TESTING 9I 



olive green upon being made alkaline with ammonia 

 the presence of boric acid is assured. 



How may the presence of formaldehyde in butter 

 be detected? 



Melt the butter at a low temperature and sep- 

 arate some of the water solution that collects at 

 the bottom. To this add milk free of formaldehyde. 

 Then test the mixture for formaldehyde by adding 

 a few drops of ferric-chlorid solution and con- 

 centrated sulphuric or hydrochloric acids, as in the 

 case with milk. A violet blue color assures the 

 presence of formaldehyde. 



How may the presence oi salicylic acid in butter be 

 detected? 



Separate some of the water solution that settles 

 to the bottom on melting the butter and follow the 

 directions given for the detection of salicylic acid in 

 milk. 



How may the presence of sulphurous acid in butter 

 be detected? 



Separate some of the water solution that settles 

 out on melting the butter. Distill off a part of it 

 and to the distillate add bromine water and barium 

 chlorid. A precipitate indicates the presence of 

 sulphurous acid or a sulphite in the butter. 



How is butter tested for its salt content? 



I. Weigh into a glass beaker 10 grams of butter. 

 Add about 20 c. c. water. Warm it to melt the 

 butter and then transfer the butter and water to a 

 separatory funnel. Insert the stopper. Shake for 



