[Illustration: FIG. 10.--Cheese-Mould (Pont l'Évêque).]
In the butter dairy, when the centrifugal separator is not used, milk is "set" for cream-raising in the milk-pan (fig. 11), a shallow vessel of white porcelain, tinned steel or enamelled iron. The skimming-dish or skimmer (fig 12), made of tin, is for collecting the cream from the surface of the milk, whence it is transferred to the cream-crock (fig. 13), in which vessel the cream remains from one to three days, till it is required for churning. Many different kinds of churns are in use, and vary much in size, shape and fittings; the one illustrated in fig. 14 is a very good type of diaphragm churn. The butter-scoop (fig. 15) is of wood and is sometimes perforated; it is used for taking the butter out of the churn. The butter-worker (fig. 16) is employed for consolidating newly-churned butter, pressing out superfluous water and mixing in salt. More extended use, however, is now being made of the "Délaiteuse" butter dryer, a centrifugal machine that rapidly extracts the moisture from the butter, and renders the butter-worker unnecessary, whilst the butter produced has a better grain. Scotch hands (fig. 17), made of boxwood, are used for the lifting, moulding and pressing of butter.
In the centrifugal cream-separator the new milk is allowed to flow into a bowl, which is caused to rotate on its own axis several thousand times per minute. The heavier portion which makes up the watery part of the milk flies to the outer circumference of the bowl, whilst the lighter particles of butter-fat are forced to travel in an inner zone. By a simple mechanical arrangement the separated milk is forced out at one tube and the cream at another, and they are collected in distinct vessels. Separators are made of all sizes, from small machines dealing with 10 or 20 up to 100 gallons an hour, and worked by hand (fig. 18), to large machines separating 150 to 440 gallons an hour, and worked by horse, steam or other power (fig. 19). Separation is found to be most effective at temperatures ranging in different machines from 80° to 98° F., though as high a temperature as 150° is sometimes employed. The most efficient separators remove nearly the whole of the butter-fat, the quantity of fat left in the separated milk falling in some cases to as low as 0.1. When cream is raised by the deep-setting method, from 0.2 to 0.4% of fat is left in the skim-milk; by the shallow-setting method from 0.3 to 0.5% of the fat is left behind. As a rule, therefore, "separated" milk is much poorer in fat than ordinary "skim" milk left by the cream-raising method in deep or shallow vessels.