BUTTERMAKING 249 
use of the improved cream ripeners and ice water attach- 
ments will result in a great improvement in both the 
quality and uniformity of butter and do away with the 
dangerous practice of adding ice directly to the cream. 
CHURNING. 
Under the physical properties of butter fat it was 
mentioned that this fat existed in milk in the form 
of extremely minute globules, numbering about 100,000,- 
ooo per drop of milk. In rich cream this number is in- 
creased at least a dozen times owing to the concentration 
of the fat globules during the separation of the milk. 
So long as milk and cream remain undisturbed, the fat 
remains in this finely divided state without any tendency 
whatever to flow together. This tendency of the globules 
to remain separate was formerly ascribed to the supposed 
presence of a membrane around each globule. Later re- 
searches, however, have proven the falsity of this theory 
and we know now that this condition of the fat is due 
to the surface tension of the globules and to the dense 
layer of casein that surrounds them. 
Any disturbance great enough to cause the globules to 
break through this caseous layer and overcome their sur- 
face tension will cause them to unite or coalesce, a process 
which we call churning. In the churning of cream this 
process of coalescing continues until the fat globules 
have united into masses visible in the churn as butter 
granules. 
CONDITIONS THAT INFLUENCE CHURNING. 
There are a number of conditions that have an impor- 
tant bearing upon the process of churning. These may 
be enumerated as follows: 
