92 THE INVISIBLE WORLD 



work. Then, into the cream thus obtained, im- 

 mediately put both the milk yeast and the butter 

 yeast. Stir well. The cream must now stand un- 

 til thoroughly ripe. If churned too soon, the but- 

 ter will not be first-class. This is because the mi- 

 crobes have not completed their best work. If 

 churned too late, the butter will be even worse. 

 This is because the proper microbes have not 

 only completed their work, but other and improper 

 microbes have come into, and taken possession of, 

 the cream, lived on certain of its ingredients, 

 and by their life processes have generated taint 

 for the butter. But, if the cream is churned 

 at exactly the right moment, the butter will be at 

 its best. 



If, at this moment, we could look into- the cream 

 with microscopic eyes, we should see^almost an 

 infinite number of minute globules. They are the 

 globules of butter. They are held together by a 

 gluey substance of the cream. The cream is sour, 

 or ripe, and therefore in just the right condition 

 for the globules to be separated. Set the churn to 

 whirling. Its centrifugal motion whirls these 

 globules together. They soon all adhere in a com- 

 pact mass. Now draw off the buttermilk. Pre- 

 pare the butter for the table. The work is com- 

 plete. 



Under this treatment success will come nearly 

 every time and uniformly. Still, even then, there 

 is the mere possibility of failure at some time. If 

 it occurs at all, it is more likely to come during 



