104 Testing Milk and Its Products. 



The specific gravity of the solids of milk is calculated by 

 means of Fleischmann' s formula 



t 



S = 



100 s-100 

 t 



s 



8 being the sp. gr. of the milk solids, s that of the milk, 

 and t the total solids of the milk. 

 Example: A sample of milk has been found to contain 13 



(103.2- 

 1.032 



per cent, of solids, sp. gr. 1.032; then 100x } L^~ 100 =3. 101; 13.0 



-3.101=9.899; ^=1.31 = the specific gravity of the milk solids. 



The specific gravity of the solids does not change if 

 the milk is watered, while it is increased when the milk 

 is skimmed. If a sample of milk of the composition 

 given in the preceding example had been watered so as 

 to reduce the solids to 11.7 per cent, and the specific 

 gravity to 1.0291 (as would be the case when 10 per cent, 

 of water was added), we would again have, by calcula- 

 tion as above, S = 1.31. If, on the other hand, the milk 

 was skimmed so as to reduce the solids to 11.7 per cent., 

 thereby increasing the specific gravity of the milk to, 

 say 1.035, we would have by substituting these values 

 in the preceding formula, 8=1.41, showing conclusively 

 that the milk had been skimmed. 



Addition of skim milk to whole milk would have the 

 same effect as skimming, as regards the composition of 

 the latter, and the specific gravity of its solids. 



The specific gravity of pure butter fat at 60 F. is .93, 

 and of the fat-free milk solids 1.5847 (Fleischmann). 

 The solids of skim milk have a specific gravity of 1.56. 

 Samples of whole milk, the solids of which have a spe- 



