The tenderness produced by roasting, we account for, from the expansion of the watery juices into steam, loosening and dissevering the fibres one from another, in forcing a passage through the pores to make their escape by. This violence, also, must rupture all the finer network of the cellular membranes, besides the smaller nerves and blood vessels which ramify so numerously through every hair’s-breadth of animal substance. This dissolution of all the minute parts of the meat, which must take place before a particle of steam can escape, will most clearly account both for the tenderness and the altered colour of roasted meat. The action of heat, also, upon the more solid parts of the bundles of fibres, will, independent of the expansion of the juices, cause them to enlarge their volume, and consequently make the smaller fibres less firmly adhesive. BROILING. Another process in which meat is subjected to the immediate action of fire is broiling, which at first sight seems not to differ from roasting. The effect on the meat is, however, considerably different. The process consists in laying chops or slices of meat on clear burning coals, or a gridiron placed over a clear fire. It is indispensable that the chops or slices be moderately thin, otherwise the outside will be scorched to a cinder before they are cooked within; from one fourth to three fourths of an inch is a proper thickness.[22] It is also necessary that the fire be moderately brisk, without smoke or flame, lest the meat should acquire a smoky taste. When a gridiron is used it ought to be thoroughly heated before the slices or chops are laid on it, to prevent them from sticking to the bars. In order to broil them equally, they must be turned from time to time till the cook can easily pierce them with a fork or sharp skewer, which is the test of them being sufficiently cooked. It is improper, however, to cut into the chops to ascertain whether they are broiled enough, because it lets out the gravy. [22] It is recommended by cooks to previously beat the raw slices with a mallet, but this practice is a bad one. Coke is the best fuel for broiling, for it does not emit any smoke, and gives a clear and moderate heat; a mixture of coke and charcoal is exceedingly well calculated for the broiling process. Those gridirons of the usual appearance and form, that have the bars fluted or hollowed on the upper side, by which means, the fat that comes from the meat that is cooked on them, is prevented from falling into the fire, and causing flame and smoke are the best; for all the grease that runs down the bars is received into a small trough, which prevents it from being wasted or lost. The upright gridiron is a still better invention, as the meat cooked on it, is entirely free from smoke, and the melted fat is still more easily saved, and kept more clean.