4 BULLETIN 98, U. S. DEPARTMENT OF AGRICULTURE. 



in ice until the next morning when observations were begun. The 

 chemical analyses of the samples were as follows: 3^ per cent milk: 

 12.68 per cent total solids, 9.18 per cent solids not fat, 87.32 per cent 

 water; 20 per cent cream: 27.27 per cent total solids, 7.27 per cent 

 solids not fat, 72.73 per cent water; 40 per cent cream: 44.30 per cent 

 total solids, 4.30 per cent solids not fat, 55.70 psr cent water. 



In view of the fact that only a single test on one sample of the 

 material was made the results can be considered only as tentative 

 and not final. 



Table I. — Specific heat of milk and cream. 



Temperature. 



Milk. 



20 

 per cent 

 cream. 



40 

 per cent 

 cream. • 



Temperature. 



Milk. 



20 

 per cent 

 cream. 



40 

 per cent 

 cream. 



"F. 



35.6 



°C. 



2.0 



3.0 



6.5 



9.0 



11.0 



13.0 



15.0 



19.0 



22.0 



24.0 



26.0 



28.0 



30.0 



32.0 





0.88 





°F. 

 95.9 

 100.4 

 105.8 

 109.4 

 114.8 

 118.4 

 123.8 

 127.4 

 131.0 

 136.4 

 141.8 

 145.4 

 150.8 



°C. 

 35.5 

 38.0 

 41.0 

 43.0 

 46.0 

 48.0 

 51.0 

 53.0 

 55.0 

 58.0 

 61.0 

 63.0 

 66.0 



0.93 



0.89 



0.86 



37.4 



0.92 



.92 



0.83 

 .90 



.80 



43.7 



.91 

 .92 



.92 



.87 





48.2 



.78 



51.8 



.93 



.96 





.87 





55.4 



.94 



.95 



1.01 



.95 



.92 



.78 



59.0 



.94 



.95 

 .94 



1.02 



1.07 



.86 





66.2 





.77 



71.6 



.93 



.86 





75.2 



.93 



.88 



.76 



78.8 



.93 





.93 



.87 





82.4 



.91 



.72 



86.0 



.92 



.88 



.94 







89.6 



.91 













The curves, figure 1, show the specific heat of 3£ per cent milk and 

 20 and 40 per cent cream at different temperatures between 35.6° F. 

 and 150.8° F. 



COHESION AND VISCOSITY OF MILK. 



Milk upon cooling assumes a denser semiliquid aspect and sticks 

 more closely to the walls of the vessel than when warm. Conse- 

 quently it is harder to clean, by means of water, a vessel that has 

 contained cold milk than one that has contained warm milk. On the 

 other hand, for the same reason, it is more difficult to cleanse vessels 

 that have contained milk by the use of cold water than by the use of 

 warm water. Milk is more liable to foam when cold than when hot, 

 and the foam will keep longer. The foam, however, will disappear if 

 the milk is heated. With the lowering of the temperature of milk the 

 cohesion increases in proportion to its viscosity. 



At 86° F. the viscosity is about 1.7 times as great in milk as it is 

 in water, while at 32° F. its viscosity is about 2.4 times that of water. 

 At 32° F. the viscosity of milk is about 2.6 times as great as it is at 

 86° F. 



