THE DAIRY. 119 



the largest are about '0005 to 'OOOG inch in diameter, the 

 smallest may be one-tenth this diameter, or even less. 

 The average size of the globules is different with different 

 breeds of cattle. The size appears to diminsh as the time 

 from calving increases. The fat globules are in most 

 cases coated with a thin albuminous covering. As the fat 

 globules have a lower specific gravity than the serum in 

 which they float, they tend to rise to ,the surface, where 

 they form a layer of cream. The largest globules are the 

 first to rise, the smallest never rise at all, being too heavily 

 weighted by their albuminous covering. Milk containing 

 an abundance of large globules is best for butter-making, 

 as the cream then quickly and perfectly rises ; but milk 

 with small globules is probably best for cheese-making, 

 as a more even distribution of fat throughout the curd is 

 then obtained. 



Milk, when it leaves the cow, will have a temperature 

 of about 90° Fahr. ; when set for cream it should be cooled 

 as quickly as possible, as changes in composition would 

 rapidly occur at a high temperature. Milk is usually set 

 for cream in shallow vessels, the depth of milk being 

 perhaps 8 inches ; in these vessels the milk stands for 

 thirty-six to forty-eight hours, till the cream has separated. 

 Under these conditions a large surface is exposed to the 

 influence of air, and a maximum amount of change takes 

 place ; the result is a decomposition of a part of the al- 

 buminoids and fats, the production of lactic acid, and 

 the partial curdling of the milk. The cream obtained in 

 this way is contaminated with curd, and contains various 

 strongly flavoured products of decomposition, which de- 

 teriorate the quality of the butter. 



On Swartz's plan the milk is placed in metal pails. 



