of 



ALr 



PROPERTIES OF MILK. 37 



to the serum than was the case while the fat was present in 

 one globule. 



For illustration, take two globules of fat having a diameter of 

 4 and 2 inches respectively. The squares would be 16 inches 

 and 4 inches respectively; their cubes would be 64 inches and 

 8 inches respectively. It will thus be seen, according to the 

 law quoted above, that the larger globule has a surface only four 

 times as great as that of the smaller one ; but the cubical content 

 of the larger globule is eight times that of the smaller one. This 

 illustrates why the large globules rise in cream quicker than 

 the small ones. In this particular instance the upward force 

 the larger globule is subjected to is eight times greater than 

 that of the smaller one, while the resistance force is only four 

 times as great as that of the small one. 



Adhesion of Milk. Normal sweet milk adheres to wood, 

 glass, and metals to a greater extent than does water. Whole 

 milk has greater adhesive properties than skimmed milk. 

 A paper moistened with milk or cream makes a label that 

 will stick to any dry object; the same paper moistened with 

 skimmed milk has less adhesive power. The adhesive prop- 

 erties of milk are also due to the condition of the nitrogenous 

 matter. This fact is made use of in painting and whitewashing. 

 Slacked lime, when mixed with buttermilk, or milk of any 

 kind, gives a whitewash which will remain on objects much 

 longer than that made by mixing with water. 



Viscosity of Milk. Milk is more viscous than water. The 

 degree of viscosity of fresh milk varies chiefly with the tem- 

 perature and fat content. So far as understood, the lower 

 the temperature, the greater the viscosity. Development of 

 acid, and high temperature lessens the viscosity of milk. Pas- 

 teurized milk or cream is less viscous than the same milk or 

 cream unpasteurized. This lack of body can again be restored 

 by adding a little viscogen, as recommended by Babcock 

 and Russell. It is advisable not to use it, however, as it does 

 not add materially to the nutritive value of milk. It merely 

 restores the body. 



