When milk has been standing for some time a spontaneous coagulation occurs, and whey is squeezed out of the contracting clot. Whey so prepared has a sourish taste, and is less palatable than the artificially prepared varieties. Whey is also artificially prepared by the addition of rennet.

To the pint of fresh milk warmed to blood heat (98 to 100° F.) add 2 tcaspoonfuls of rennet, set it aside in a warm place for a quarter of an hour, when clotting will have occurred. The clot is then very thoroughly broken up by stirring, and the whole strained through muslin. The whey has percentage composition of water 93, lactose 5, albumin .8, ash .6, fat 3. It is practically an aqueous solution of milk sugar. It is apt to turn sour.

Whey can also be prepared from milk by boiling with lemon juice, e.g., boil a pint of milk with 2 teaspoonfuls of lemon juice. Strain in muslin; squeeze out all fluid from the curd. The whey can be added to beef-tea, or yolk of egg beaten up in hot water.

Whey may be similarly prepared by boiling two parts of milk with one part of white wine, e.g., sherry.

Whey makes a palatable drink, with slightly diuretic and laxative properties. Whey cures, where up to 5 pints of the whey are taken in twenty-four hours, have been established for the treatment of renal and dropsical affections (see p. 538).