A guide to modern cookery

the water is to assist in the melting, and this it does by filtering into the grease, vaporising, and thereby causing the latter to swell. So long as the water has not completely evaporated, the grease only undergoes the action of liquefaction, _i.e._, the dissolution of its molecules; but its thorough cooking process, ending with its purification, only begins when all the water is gone. The grease is cooked when (1) the membranes which enveloped it alone remain intact and are converted into greaves; (2) it gives off smoke which has a distinct smell. At this stage it has reached such a high temperature that it is best to remove it from the fire for about ten minutes, so that it may cool; then it must be strained through a sieve, or a coarse towel, which must be tightly twisted. 264—THE VARIOUS DEGREES OF HEAT REACHED BY THE FRYING MEDIUM, AND THEIR APPLICATION The temperature reached by a frying medium depends upon the latter’s constituents and its purity. The various degrees may be classified as moderately hot, hot, very hot. The expression “boiling hot” is unsuitable, seeing that fat never boils. Butter (an occasional frying medium) cannot overreach 248° F. without burning, whereas if it be thoroughly purified it can attain from 269° to 275° F.—a temperature which is clearly below what would be needed for work on a large scale. Animal greases used in ordinary frying reach from 275° to 284° F. when moderately hot, 320° F. when hot, and 356° F. when very hot; in the last case they smoke slightly. Pork-fat (lard), when used alone, reaches 392° F. without burning. Very pure goose dripping withstands 428° F.; and, finally, vegetable fats may reach, without burning, 482° F. in the case of cocoa-nut butter, 518° F. with ordinary oils, and 554° in the case of olive oil. The temperature of ordinary frying fat may be tested thus: it is moderately hot when, after throwing a sprig of parsley or a crust of bread into it, it begins to bubble immediately; it is hot if it crackles when a