96 MANUAL OF MILK PRODUCTS 



although when milk is drawn directly into a solution of these 

 alkalies, the grouping is entirely prevented. A satisfactory 

 explanation of this phenomenon has not yet been found. Differ- 

 ent alkalies and alkaline earths have been tried in this connec- 

 tion, but none of them has any effect on the microscopic appear- 

 ance, except in the case of calcium hydrate, which increases the 

 tendency of the fat globules to aggregate in a marked degree. 

 The significance of this specific reaction will be considered in the 

 succeeding article. 



Conclusion 



The consistency or body of milk and cream is due to : 



1. The viscosity of the serum imparted by solids in solution. 



2. The mechanical state of suspended substances (fat, etc.). 

 The casein exerts a greater influence on consistency than fat, and 

 in milk is a chief factor ; in cream the fat assumes a more im- 

 portant role because of its high percentage. The aggregations 

 of fat globules also have a very important influence in determin- 

 ing the consistency of milk and especially cream. 



THE SPECIFIC HEAT OF MILK AND MILK DERIVATIVES (Hammer 



and Johnson) 1 



In a great many dairy processes where heat is used, the 

 amount and intensity of the energy necessary to gain a certain 

 end-product are very important. These factors are important 

 not only because heat, like material commodities, is an item of 

 expense, but also because too great an intensity of temperature, 

 or too prolonged an application, may cause serious chemical 

 and physical changes in the substance worked with. 



The amount of heat which it takes to raise unit weight of a 

 substance unit temperature depends, first, upon its chemical 

 nature and, second, upon its physical state. 



1 Iowa Research Bui. 14. 



