22 MILK 



Babcock's formula has been much used in the 

 United States. It is adapted to calculating the 

 solids not fat. In this formula g is the entire 

 figure for sp. gr. referred to water as i. 



Snf = ( ^°°g-/g - I ) X 2.S (loo -/) 

 \ioo- 1.0753 /g / -^ ' 



Babcock has also given a much simpler form 

 adapted for total solids. This differs but slightly 

 from Richmond's. 



Total Proteins. — 3 types of processes are 

 employed for this estimation : Calculation from 

 the total nitrogen; precipitation and direct 

 weighing; calculation from the "aldehyde-figure." 

 Milk contains appreciable amounts of non- 

 protein nitrogen, but the fact is usually disre- 

 garded. According to Munk, this may range, in 

 cow's milk,, from 0.022 to 0.034%, and from 

 0.014 to 0.026% in human milk. By these 

 figures, the average protein nitrogen in cow's milk 

 would be 94%, and in human milk 91%, of the 

 total nitrogen. 



, Kjeldahl-Gunning Method. — (Calculation from 

 total nitrogen). 

 Reagents : 



Potassium sulfate. — A coarsely powdered form 

 free from nitrates and chlorids should be selected. 



Sulfuric acid. — This should have a sp. gr. 

 1.84 and be free from nitrates and ammonium. 



