Cheese Factories in Derbyshire. 
53 
loss of heat by evaporation is prevented. Inequality of tempera- 
ture produces curd of different kinds, the greater heat causing the 
action of the rennet to be more decided, consequently the curd 
becomes tough. It is no uncommon occurrence to have one part 
of the curd in the same vat tough and the other part free and 
open ; this difficulty will, however, be readily overcome, as the 
system of applying the heat is capable of great improvement. 
When the milk in the vats has been raised to the desired tem- 
perature, the annatto is added, if colouring is used, and the 
whole mass well stirred. The quantity of annatto will depend 
on the shade desired : this once settled, the rest will be easy ; the 
quantity of milk being always known, the colour can be regulated 
accordingly. The rennet is now put in and the milk again well 
stirred and the vat covered over, as before described. Good 
rennet will coagulate 1500 times its own weight of milk ; its 
action is more rapid when the milk is slightly sour. When this 
is the case the whole operation should be performed more quickly. 
The thicking process is accelerated with the increased tem- 
perature up to 120^ ; at ISS'^ it becomes inoperative and loses 
its vitality. The quantity of the rennet causes more diversity 
in the taste and flavour of the cheese than anything else. In 
America filtration has been tried successfully. I have tried 
some experiments on a small scale : by passing the liquid through 
wood-charcoal, placed in a flannel bag, the active principle 
remains unimpaired. I think the adoption of some such simple 
means may lead to important results. Under ordinary circum- 
stances the curd will be ready to cut in from 30 to 40 minutes 
after the rennet is added. In manv English dairies the curd is 
still broken by hand, instead of being cut, as is now universally 
the case in all the American factories. The best time to perform 
this operation is when the curd has obtained sufficient consistency 
to break smooth, without whitening the whey and before it 
becomes tough. The cutting should be done as carefully and 
evenly as possible, with despatch, but with as little motion as 
may be. It is first cut into prisms from bottom to top ; it is then 
cut parallel to the surface, dividing the prisms into cubes. The 
knives used for cutting the curd are of two kinds ; in the one the 
blades are vertical and in the other horizontal. In America there 
is considerable difference of opinion as to whether the curd should 
be cut into large or small pieces. Coarse curd invariably gives a 
greater quantity of cheese from a given quantity of milk, as less 
casein and buttery matter pass off in the whey during the pro- 
cess of making. The objection to coarse curd is its liability 
to produce open and uneven texture, and inferior flavour, from 
a portion of whey becoming hermetically sealed in the centre 
of large lumps of curd during the process of cooking, and thus 
