2. _To produce certain chemical changes._ Thus, starch is partially converted into dextrine; gelatin is formed from connective tissue, etc. 3. _To destroy any noxious parasites_ present in the food, or obviate any ill effects from _putrefactive changes_. Diseased meat chiefly produces bad effects when imperfectly cooked. 4. _To make the food more pleasant_ to the eye and agreeable to the palate. The improved savour in cooked meat, for instance, has a very appetising effect, and consequently makes digestion easier. THE COOKING OF FLESH.—1. =Roasting= is, perhaps, the most perfect way of cooking meat. It exalts its flavour more than any other method. In roasting, place the meat at first sufficiently near a brisk fire, so that the albumin on its surface may be readily coagulated, and the juices retained in the interior of the joint. After about fifteen minutes, the joint ought to be removed somewhat further from the fire, and allowed to cook slowly. Frequent basting is desirable to obtain a good result. Brown meats, such as beef, mutton, and goose, require a quarter of an hour per pound weight; veal and pork require about ten minutes additional, to ensure the absence of redness. White-fleshed birds require a somewhat shorter time. The time required in roasting will be a little more if the joint is large, or the fire not very clear. To ascertain if the meat is sufficiently cooked, press the fleshy part; if it remains depressed, it is done; if not done, it retains its elasticity. At the first incision, gravy should flow out of a reddish colour. _The changes undergone_ during roasting are, that the connective tissues uniting the muscular fibres is converted by the gradual heat into gelatin, which is soluble and easily digested; the muscular fibres, consequently, become more separable, and the myosin of which they consist is rendered more digestible. The fat is partly melted out of its fat cells, and partly combines with the alkali from the blood-serum. Empyreumatic oils (_i.e._ fat partially burnt), developed by charring of the surface of the joint, are carried off when it is roasted in front of the fire; and so, to a large extent, is acrolein. Acrolein (C₃H₄O) is always produced by the destructive distillation of neutral fats containing glycerine, and is the cause of the intolerably pungent odour accompanying the process. Osmazome, a peculiar extractive matter, on which the flavour and odour of meat depend, is developed better by roasting than by any other method of cooking. It is useful to remember, in buying beef or mutton, that 20 per cent. must be allowed for bone and 20 to 30 per cent. for the loss during cooking. The following figures are by Johnston: IN ROASTING. IN BAKING. IN BOILING. 4 lb. of mutton lose in weight 1 lb. 6 oz. 1 lb. 4 oz. 14 oz. „ beef „ „ 1 lb. 5 oz. 1 lb. 3 oz. 1 lb.