134 ANIMALS AND THEIR PRODUCTS. 



put them into the right circumstances^ as to temperature 

 and exposure to air. 



241. At 40° Fahrenheit, you might churn from Ja- 

 nuary td March, or at 100°, you might churn from 

 June to September, and no butter would come. Or if 

 you were to exclude the air entirely from the inside 

 of the churn, you might roll that churn, with the 

 cream in it, from Cape Horn to Labrador, and the 

 butter would not come. 



242. All the processes of nature have their condi- 

 tions. The separation of butter from curd is one of 

 these processes. The conditions must he complied with. 

 We will suppose that the cream is from cows that give 

 good milk. The farmer is unwise who keeps any 

 other. Some cows' milk will not give much butter, 

 for there is not much butter vs^ it. We will suppose 

 also that the milk has been kept at a temperature 

 about medium between freezing and summer heat ; 

 that the cream has been taken off while the milk was 

 yet sweet, and has been kept in a cool place till it was 

 a little sour, or was very near the point of souring; 

 that it is now put into a clean churn, and brought up 

 to a temperature of about 60° Fahrenheit, gradually 

 and without much stirring; and that we now begin to 

 lift the dasher, or turn thfe crank, as the case may be, 

 either forcing air into the cream by some patent 

 contrivance, or at least letting air have free access to 

 its surface, and now let us see what happens. 



243. By stirring the cream we change the surface 



