The small cows of the Alderney or Guernsey breed afford the richest milk. In some parts of the country few other cows are kept; but they are not so hardy as many other breeds, they do not yield the large quantity of milk, and are therefore not great favourites with dairy farmers. The quality and wholesomeness of the milk depends greatly on the food and home of the animal. Large numbers of cows are kept in confined, ill-ventilated buildings, and are fed upon brewers' grains, so that the milk is thin and poor, and unfit for food. Milk from an animal in a state of disease cannot but produce ill health to the consumer. Of late years model dairies, under medical inspection, have been established in the neighbourhood of London, and have, no doubt, had a share in improving the health of the Metropolis. Milk may also be a carrier of infectious disease from the farm where it is produced to the consumer. The "milk epidemics" of fever are instances of this. It is, therefore, advisable to buy milk only at places where reasonable precautions for its wholesomeness are known to be taken, and failing this knowledge—perhaps in all cases—milk should be boiled.
Adulterated Milk.—Milk is more frequently adulterated with water than with anything else. The best popular test for adulteration by water is by means of a small instrument called a lactometer. It is useful, but not infallible, for it is based upon the fact that the specific gravity of milk is (as has been said) 1.032. But cream is lighter than milk; and, therefore, it sometimes happens that milk with an excess of cream will not stand the test so well as skimmed or poor milk. However, this fault is rare, for it is not an uncommon practice to make butter of all or part of the cream, and then to sell skimmed milk for fresh. This is easier now that mechanical separators have in large dairies almost superseded the old plan of allowing the cream to rise. By the old plan, the 12 hours that the milk stood was sufficiently long in the summer for it to turn sour, when it was no longer fit for sale, and generally went to fatten pigs. Now, while the milk is yet warm from the cow, it is put into a large reservoir, from which it is conducted along a series of metal pipes, where it rapidly cools. Then it trickles into the separator, and is whirled at a very rapid speed, the result being that the light cream is thrown to the top, while the heavier milk is drawn off below, completely skimmed and perfectly fresh.
To Keep Milk.—For the preservation of milk, scrupulous cleanliness is the first necessity. Not only must the pots and pans be scrubbed and scalded (that every dairy woman understands, at least, in theory), but the dairy must be clean and well ventilated; in it no open drain, no meat or game hanging; outside it no foul heap of yard refuse or decaying matter. Nothing is more certain to taint the milk and spoil the butter than neglect of these precautions.
Boiling milk preserves it; this is one great advantage of the Devonshire method of butter making for small dairies. And we have already spoken of the addition of soda or borax, Soda may very well be put