CHAPTEE V. 

 BABCOCK TEST FOR OTHER MILK PRODUCTS. 



97. Skim milk. Each division on the scale of the neck 

 of the regular Babcock test bottle represents two-tenths 

 of one per cent. (44). When a sample of skim milk or 

 butter milk containing less than this per cent, of fat is 

 tested, the estimated amount is expressed by different 

 operators as one-tenth, a trace, one-tenth trace, or one- to 

 five-hundredths of one per cent. Gravimetric chemical 

 analyses of skim milk have shown that samples which 

 give only a few small drops of fat floating on the water 

 in the neck of the test bottle, or adhering to the side of 

 the neck, generally contain one-tenth of one per cent, of 

 fat, and often more. Samples of skini milk containing 

 less than one-tenth of one per cent, of fat are very rare, 

 and it is doubtful whether a sample of separator skim 

 milk representing a full run of say 5,0001bs. of milk, has 

 ever shown less than five-hundredths of one per cent, of 

 fat. Under ordinary factory conditions, few separators 

 will deliver skim milk containing under one-tenth of one 

 per cent, of fat, when the sample is taken from the whole 

 day's run. This must be considered a most satisfactory 

 separation. 1 



98. The reason why the Babcock test fails to show all 

 the fat present in skim milk must be sought in one or 

 two causes: a trace of fat may be dissolved in the sulfuric 

 acid, or owing to the minuteness of the fat globules of 



i For comparative analyses of separator skim milk by the gravimetric 

 method and by the Babcock test, see Wis. exp. station, bull. 52 and rep. 

 XVII, p. 81. 



