1 88 MILK 



Gerber's method, if carefully carried out, gives excellent results 

 comparable with those obtained by the most accurate of the 

 direct extraction methods, such as Adam's method (p. 185). 



Relation between Specific Gravity, the Pat, and 

 Total Solids. 



It has been found that in fresh milk there is a relation between 

 the specific gravity, the fat, and the total solids, so that if the value 

 for two of these be known, the third can be calculated and a 

 method of control thus obtained. 



Fleischmann has worked out the following formula from a 

 large number of experimental results :— 



T = i.2F+2.665('°°|-'°°) 



where 



T = total solids expressed in percentage, 

 F = fat expressed in percentage, 

 S = specific gravity of the milk at i5°C. 

 Many other formulae have been proposed, Richmond suggesting 

 an adaptation of the above : 



T=i-2F + .25 D + .14, 

 wherein the letters have the same significance as above, excepting 

 that D = lactometer degrees. 



D 

 One of the simplest formulae is T== F+ 5 (proposed by 



•8 

 Halenke and Moslinger), which may be conveniently written 



as T = — + -^ F (for ease in committing to memory). These last two 



4 4 

 formulae do not employ a constant depending on the specific gravity 

 of the total solids not fat, as do the other formulae given above. 



All these formulas, which however do not apply to old milk, 

 give practically the same results, and should be used to check the 

 results obtained in previous determination of the specific gravity, 

 total solids and fat (pp. 177-185), provided these have been carried 

 out with the same sample of milk. 



Nitrogenous Substances. 



The nitrogenous substances (proteins) present in milk are 

 casein, lacto-albumin and lacto-globulin (see p. 175). 



The casein may be conveniently precipitated by suitable 

 reagents and estimated quantitatively, while the lacto-albumin is 



