THE MILK CONTRACTOR 259 



to produce clean milk. That clarifiers are useful seems evident from their 

 wide adoption. Through the courtesy of the Boston Biochemical Lab- 

 oratory there are presented in Table 76 data showing the effect of clari- 

 fication of milk as exemplified by two different makes of clarifiers and in 

 Table 77 analyses of clarifier slime. 



Bahlman showed by analysis that clarifier slime was 60 per cent, mois- 

 ture and 40 per cent, solid matter and that it carried 950,000,000 bacteria 

 per gram. The dried slime was 83.36 per cent, organic and 14.64 per cent, 

 mineral matter. Dried powdered slime contained the constituents shown 

 in Table 78. 



TABLE 78. CHEMICAL ANALYSIS OF CLARIFIER SLIME (BAHLMAN) 



Protein (N X 6.38) 67.9 largely casein. 



Fat 3.4 partly derived from epithelial cells and 



other organic detritus. 



Milk sugar 7.8 normal milk constituent. 



Crude fiber 2.2 



Silica 3.8] 



Oxide of iron 0.5? derived from earth contamination. 



Oxide of aluminum . 6 j 



Calcium phosphate 3.6 a normal milk constituent. 



Potassium phosphate 6.2 a normal milk constituent. 



Sodium and potassium chlorides ... 0.1 a normal milk constituent. 



96.1 



Undetermined . . . . v. 3.9 accounted for by protein factor used, and 



by the SiO 2 and Fe 2 O 3 existing in the 

 slime as hydrates, 



It therefore appears that the residue consists very largely of normal 

 milk constituents. The amount of material removed of course varies in 

 different milks. Bahlman found that in one run, in which 725 gal. of 

 milk passed through the machine, 2.5 Ib. of slime were deposited which is 

 1.6 grams of moist slime to the gallon. He concluded that though large 

 numbers of bacteria were contained in the slime, the percentage removal 

 probably was not great, since the milk is exposed to the separating action 

 for only a brief period. 



He found that by recentrifuging clarified milk in the laboratory for a 

 longer time and at a lower speed, more sediment was thrown out thus 

 showing that the clarifiers do not remove all the matter that it is possible 

 to, by centrifugal force. 



Hinkelman by passing a gallon of milk on the verge of souring, re- 

 peatedly through the clarifier was able materially to reduce its bacterial 

 count and delay its souring several hours. It is his belief that bacteria 

 of different species are of different weights and therefore that some species, 

 being heavier than others, in the process of clarification separate out more 

 completely. From experiments he has made he concludes that strepto- 



