Setting and Cutting 253 
temperature of the milk. So soon as the rennet is 
added, the milk should be quickly and carefully 
stirred, so that the rennet may be uniformly mingled 
with every part of it. This stirring should continue 
until the mixture of rennet and milk is complete, 
but should stop before any appearance of coagula- 
tion. The milk in the vat is then allowed to be- 
come quiet, and remains undisturbed while the pro- 
cess of coagulation is going on, the object being to 
secure a uniformly solid clot or coagulum through 
the mass. The action of the rennet is not instanta- 
neous; the first appearance of coagulation is noticed 
by a slight thickening of the milk. This gradually 
increases until the whole mass is solid, and if left 
undisturbed the action of the rennet continues to 
contract the coagulated casein and cause a_ partial 
separation of the whey. As soon as the coagulation 
is strong enough, so that the casein will maintain 
its shape when broken, the contents of the vat are 
ready for the next step in the process. 
Period IT., cutting.—The curd, as the coagulated 
casein is called, is ready for cutting when under 
strain it will break with a clean fracture. This is 
conveniently tested by gently inserting the finger in 
the curd in an oblique position and slightly raising 
it, when if the curd breaks clean across the finger 
it is sufficiently firm for cutting. Cutting is per- 
formed in order to facilitate the further contraction 
of the casein and the expulsion of the whey. For- 
merly the solid mass of curd was broken up into 
small pieces by any sort of an instrument that 
