UNSWEETENED CONDENSED MILK DEFECTS 259 
separates and the difficulty of overcoming this defect, differ 
greatly with locality and season of year. The fat globules in 
milk from the Channel Island breeds, average two to three times 
as large as those in milk from the Holsteins and Ayrshires. 
Therefore, factories located in Holstein and Ayrshire territories 
are not troubled nearly as much with fat separation in evap- 
orated milk, as factories in localities where Jerseys and Guernseys 
predominate. 
Again, the fat globules are largest at the beginning of the 
period of lactation and decrease in size as the period of lactation 
advances. 
In order to equalize the output of evaporated milk through- 
out the year, condensing concerns make every effort to induce 
their patrons to time the breeding of their cows in such a way 
that the fresh cows are distributed throughout the year. The 
result of this practice is, that the milk supply of these factories 
represents at all times a mixture of milk from cows at all stages 
of their period of lactation. "This naturally equalizes the be- 
havior of the finished product as far as separation of the fat is 
concerned, facilitating the control of this separation. On the 
other hand, in localities of factories, newly established, summer 
milk is largely produced and the majority of cows freshen in the 
spring. This causes a marked increase of the size of the average 
fat globules in early summer, rendering the manufacture of 
evaporated milk, that does not separate its fat, more difficult. 
Effect of Degree of Concentration.— Other conditions being 
the same, the more concentrated the product, the less the danger 
of fat separation in the finished product. The ieason for this 
lies in the fact that with the concentration the viscosity and the 
resistance force of the evaporated milk increase, hindering the 
fat globules in their upward passage. This is partly offset by 
the increase in the specific gravity of the product, but the in- 
crease of the resistance force exerts a stronger influence against 
separation of the fat, than the increase of the gravity force exerts 
in favor of fat separation. 
However, as the concentration increases, the evaporated 
milk becomes more sensitive to the sterilizing process and 
beyond certain limits it would be necessary to reduce the tem- 
perature or the length of exposure to heat, or both, in order to 
