io DAIRYING 



standing from 12 to 48 hours. The temperature of the milk dur- 

 ing this period is the same as that of the surrounding air and 

 varies with the seasons of the year. The temperature of the room 

 in which the milk is set should control the depth of the milk, if 

 the room has a temperature of 60 degrees Fahr., three inches is 

 deep enough, and some idea of the rate at which the cream rises 

 at this temperature is shown by the following observations : 



227. When set at 60 degrees Fahr. the percentage of the fat 

 in the milk that was recovered in the cream was as follows : 



After standing 8 hours 43.5% or at the rate of 5.44% per hour. 



The following 8 hours 11.5% or at the rate of 1.44% per hour. 



The following 12 hours 11.4% or at the rate of 0.95% per hour. 



The following 12 hours 6.7% or at the rate of 0.56% per hour. 



Total, 40 hours 73.1% 



The higher the temperature at which the milk is set the richer 

 the cream and the smaller the quantity of cream obtained. 



AYhen set in this shallow layer the fat globules do not have 

 far to rise to reach the surface ; the cream separation therefore 

 begins at once. The cream which rises first is rather thin, but it 

 gradually thickens by standing, and if the room is warm and dry 

 there is so much milk surface exposed to the air that the constant 

 evaporation makes a rather tough, leathery cream. This drying 

 of the cream may be somewhat overcome by setting the pans of 

 milk in a well ventilated basement or cellar, where the air is 

 partially saturated and where the temperature does not go b.elow 

 60 degrees F. 



Condition of Cream When Skimmed. 



228. If sweet cream for the table is wanted, the milk must 

 be skimmed before the souring process has begun. It is, however, 

 very difficult to skim off such cream without losing a considerable 

 quantity of it by the mixing which is nearly unavoidable when 

 the skimming is done. Not much more than one-half the cream 

 in milk is obtained when it is skimmed sweet by this process. 



