196 DAIRY FARMING 



while hot. The residue on the filter paper is the albumin. The sugar 

 and the ash remain in the filtrate. 



18. Milk Sugar. The milk sugar is not easily separated from 

 the ash. Its presence may be demonstrated by using Fehling's 

 solution as follows. To 10 c.c. of the filtrate add 5 c.c. of Fehling's 

 solution and boil. The red precipitate shows the presence of sugar. 



19. Ash of Milk. The presence of ash may be demonstrated as 

 follows. Take 25 c.c. of milk in an evaporating dish. Add a few 

 drops of acetic acid. Place evaporating dish and contents on a sand 

 bath and evaporate to dryness. Allow to char slightly, then place 

 on a wire gauze over a gas burner and heat until contents char. Re- 

 move the gauze and heat over a full flame until all of the carbon is 

 burned off. The gray residue is the ash, or mineral matter. 



THE BABCOCKTEST FOR MILK 



20. Test of Whole Milk. Apparatus needed : a hand power cen- 

 trifuge or testing machine, 4 to 6 milk test bottles, a pipette to 

 measure the milk, an acid measure, ordinary commercial sulfurio 

 acid, a small sample of milk, and some hot water. The apparatus 

 may be purchased from any dealer in dairy supplies. Sulfuric acid 

 may be obtained at any drug store. 



Sampling the Milk. The accuracy of the test depends largely on 

 the sample taken. The milk to be tested should be thoroughly 

 mixed, preferably by pouring several times from one jar to another. 

 The milk should be at ordinary room temperature. The small end 

 of the pipette is placed in the milk and the milk drawn in by suck- 

 ing slowly at the upper end. The milk is drawn somewhat above 

 the mark which indicates 17.6 c.c., and the first finger is then quickly 

 slipped over the top of the pipette. The milk is then allowed to 

 escape slowly until the surface is at the mark on the pipette. The 

 small end of the pipette is now placed in the neck of the test bottle 

 and the milk allowed to flow into the test bottle. The last drop 

 remaining in the point of the pipette should be blown out into the 

 test bottle. It is always well to make duplicate tests of each 

 sample. 



Adding the Add. When all the samples are measured out, the 

 acid should be added. The acid measure is filled to the 17.5 c.c. 

 mark with acid that is at room temperature. The acid is now 

 poured into the test bottle, holding the bottle in an inclined position 

 so that it runs down the neck and side of the bottle and forms a 

 clear layer at the bottom. Next take the bottle by the neck and 



