The usual methods of cooking are roasting, broiling, boiling, frying, stewing, and decocting. We will consider each process briefly, from the point of view of practical chemistry.

In roasting, the exterior of the piece of meat is submitted brusquely to a temperature considerably above 212 degrees Fahrenheit or boiling-point, or at any rate not be-low boiling-point. The result is that the albumen of the surface is coagulated, and in this state acts as a barrier against the escape of the juice inside, and against the infiltration of liquid from without. After a few minutes close exposure to a brisk, clear fire, the joint may be drawn back a little and roasted slowly. Thus the interior mass of the meat, enclosed in an impervious jacket, cooks literally in its juice, getting heated in the inside only to a temperature between 120 and 150 degrees Fahrenheit, which is not sufficient to coagulate and harden the interior albumen. By this outer dried layer the meat inside is protected from evaporation and desiccation, and, being acted on by the liquid juice, it undergoes a maceration and a temperature sufficient to disintegrate the muscular fibre, to gelatinize and render soluble the connective tissue that binds the fibres together, and to develop the aroma enough to make the meat agreeable to the taste. What the aroma is remains a mystery. All we know is that it comes from the brown sapid substance produced on the outer layer of the flesh by the operation of roasting. In this part of the meat, according to Bloxam, "some of the constituents of the juice suffer a change which gives rise to the peculiar flavor of roast meat."

Broiling requires a brisk fire, free from smoke, the combustible being either charcoal or coke. The fire should extend somewhat beyond the edges of the gridiron, in order that the sides of the meat may be acted upon by the heat at the same time as that portion which is in more immediate contact with the fire.

The albumen over the entire surface of the piece of meat, whether cutlets, chops, steak, kidneys, or what not, should be rapidly coagulated, so as to prevent the escape of the juice.

Always take care to have your fire brisk and clear at the beginning of the operation, so that you may be sure of rapidly setting the whole surface of your meat - glazing it, so to speak - for the coagulation of the surface albumen forms an impervious jacket for the grilled meat, just as it does for the roast and the boiled meat, as already described.

Let your gridiron be hot before you put your meat on it, otherwise the cold bars, conducting away the heat and preventing rapid coagulation of the surface albumen, will cause an escape of juice into the fire.

In order to prevent sticking, the gridiron, before the meat is put on it, should be rubbed over with suet. For grilling fish the grid-iron may be rubbed with chalk.

The gridiron is made to incline gently towards the cook, who, being intelligent, and having comprehended all that we have said about the necessity of carefully imprisoning the juice of meat and never piercing the outside coating of coagulated albumen, will, of course, never dream of turning his chops or steaks with a fork - he will grasp them with a pair of special tongs, or even with his fingers. In practical kitchen-work one is constantly reminded of the truth of the familiar saying that fingers were made before forks, and also before tongs.

The operations of stewing invariably begin by browning the meat in a little butter or dripping in a saucepan or a frying-pan. The object is precisely the same as in the operations of roasting, boiling, and broiling: namely, to coagulate the surface albumen of the meat, and so case-harden it and develop its flavor in accordance with the chemical principles already set forth.

Frying is the process of subjecting food to a high temperature in a bath of hot fat, which, at the moment of beginning the operation, should be about 400 degrees Fahrenheit. During the operation the temperature of the bath should rise two or three degrees.

The best frying-bath is one composed of beef suet and veal fat in equal proportions, melted down ; the grease of the dripping-pan and of the pot-au-feu is also good; lard, too, may be used, although it leaves the surface of the fried food less pure; a special oil is also sold for frying purposes, and butter maybe employed for light frying only. Ordinary olive oil, when heated to a high temperature, contracts a strong taste, probably due to the charring of particles of the flesh of the olive that remain imperceptibly mixed with the oil.

Note that cook-books generally recommend the use of a beaten egg to make the flour, bread-crumbs, or chapelure adhere to a sole, for instance, which is to be fried. A simpler method is to dip the sole in milk and then roll it in your flour. Thus you avoid the thick lumps and patches of crust which are almost inevitable when an egg is used. This is a small detail, but small details all "make for" perfection, as Matthew Arnold would have said.

Experience will teach the cook to discover when the frying-bath has reached the required temperature by the peculiar hissing sound produced by allowing a drop of water to fall into it.

Decoction is the name that may be given to the process of extracting the juice from meat and separating it from the fibre and tissues; it is the reverse of roasting or broiling and their derivative processes. In order to extract the juice of meat we place the flesh in cold water, the temperature of which is very slowly raised to the boiling-point: thus all the juice of the flesh is dissolved out and completely separated from the muscular fibre.

Bloxam says: "The object to be attained in the preparation of beef-tea is the extraction of the whole of the soluble matters from the flesh, to effect which the meat should be minced as finely as possible, soaked for a short time in an equal weight of cold water, and slowly raised to the boiling-point, at which it is maintained for a few minutes. The liquid strained from the residual fibrine contains all the constituents of the juice except the albumen, which has been coagulated."

The economical French, in making their pot-au-feu and bouillon, do not mince the meat, but leave it in a solid mass, the only reason being that thus the meat may be presented at table, although there is very little nourishment left in it after the process of decoction is over.

In boiling, the meat is exposed to a high temperature in water. You wait until the water has reached the boiling-point before you immerse the meat in it, and leave it to cook for about five minutes at that temperature. The heat of the water, 212 degrees Fahrenheit, at once coagulates the albumen in the external layer of flesh, which becomes thus a waterproof case in which the meat cooks, safe from the infiltration of water and from the escape of its juice. After the first five minutes the cooking should proceed more gently, at a temperature of 162 degrees Fahrenheit.

Both in roasting and in boiling, the result is similar, and is thus noted by Dalton on the preparation of meat for food :

"Firstly, the albumen which is present in the muscular tissue is coagulated, and the muscular fibres, therefore, become rather firmer and more consistent than they are in fresh meat.

"Secondly, the cellular tissue between the muscular fibres is softened and gelatinized, so that the fibres are more easily separated from one another, and the whole mass becomes more tender and easily digestible.

"Thirdly, the high temperature develops in the albuminous ingredients of the meat a peculiar and attractive flavor, which they did not possess before, and which excites in a healthy manner the digestive secretion, thus serving not only to please the taste, but also to assist in the digestion of the food.

"Raw meat," adds Dalton, "is usually insipid and unattractive. It is only after it has been subjected to a certain amount of cooking that the desired flavor makes its appearance, by which the appetite is stimulated, and the nutritive qualities of the food consequently improved.

"The preparation of meat in cooking should be carefully managed so as to accomplish the results above described. For if the heat be insufficient the proper flavor will not be developed; and if the heat be excessive, the meat, instead of being cooked, will be burned and decomposed, and thus rendered useless for the purpose of nutrition."

Notice how constantly science recurs to the physiological advantages of delicate cooking, in that it stimulates the appetite, pleases the taste, assists in the digestion, and actually improves the nutritious qualities of food.

Before cooking meat, a sufficient time must have elapsed since the slaughtering to have allowed the cadaveric rigidity to pass and the spontaneous reaction to set in which determines a primary disintegration of the tissues. The time which meat has to be kept varies according to the temperature. If cooked while in a state of cadaveric rigidity, that is to say, too fresh, meat is hard and indigestible.

The first practical lesson to be drawn from the above theory of roasting is that a joint should never be spitted by thrusting an iron rod through it. The only reasonable and scientific spit is a sort of cage which clasps the meat around without piercing it anywhere. Thus there will be no loss of juice.

The rational way of placing the spit is in a horizontal position, and care should be taken to have the fire in a somewhat convex form, so that the heat may be distributed over the ends as well as over the middle portions of the meat.

Baked meat is an abomination.

So-called "roast" meat, cooked in ovens, is a delusion and a snare.

Roast meat is roast meat, and in order to roast you must have an open fire, before which your joint is placed in such a manner that the air circulates freely around it.

The reason why it is objectionable to cook meat by baking it in an oven - unless it be a big bakers' oven - is that it is difficult, if not impossible, to keep an ordinary oven, in a cooking-stove, clean and well - ventilated. The sides, roof, and floor of the oven get bespattered with particles of fat and spots of gravy during the baking process, and these particles become charred, and thus fill the oven with ammoniac and with a foul atmosphere of empyreumatic oils, by which terrible word the chemists indicate the unwholesome vapors generated through the action of fire.

In the process of roasting before an open fire these empyreumatic odors are, indeed, generated, but they pass off up the chimney, whereas in the oven they are imprisoned, and there penetrate the meat, destroy its flavor, and render it more or less insipid.

Meat, however, may be baked in pies, because in this case its surface, being protected by the crust, cannot be charred and impregnated with the foul empyreumatic oils. The baking of meat in a pie-crust amounts, in reality, to a stewing operation, the paste forming, as it were, a stew-pan with its lid.

Frequent basting is essential to successful roasting. Otherwise, the coagulated surface of the meat would crack and split open during the operation, and allow an escape of the juice. The melted fat, poured over the meat, penetrates into every crevice, and by means of the higher temperature of the fat the surface of the meat is maintained in an impervious state.