130 CHEESE AND CHEESE-MAKING 



every dairy school, the greater portion of the 

 curd will be removed, and almost pure butter- 

 fat left behind. 



Let us, however, assume that inferior butter is 

 produced in a dairy, and that the occupier is 

 unable to improve the quality. It may be asked 

 how the production of an inferior article can be 

 converted into the production of one of really 

 high quality. The thing is easy if the work is 

 carried out with intelligence and thoroughness. 

 The manufacturer must condescend to details and 

 recognize scientific facts. The alteration which 

 takes place in cream, that is to say its change from 

 perfect sweetness to a condition of sourness, 

 acidity, or ripeness, is owing to the presence of an 

 organism or bacterium which can only be dis- 

 covered by those who are skilled in the use of the 

 microscope. This organism rapidly increases in 

 number when milk is warm and exposed to the 

 atmosphere. It converts the sugar of milk into 

 lactic acid ; hence the^ourness of milk. If this 

 change is allowed to continue unchecked, the curd 

 of the milk will coagulate, and it is for this reason 

 that cream when allowed to ripen for churning 

 becomes thicker. If cream is churned while it is 



