The following are the more important uses of milk: 1. As an infant food.

2. As a food for adults.

3. As a source of special food products and derivatives, such as koumiss, cream, butter, and cheese.

4. As a diuretic.

5. For its soothing effect on diseased mucous membranes of the alimentary canal.

6. To loosen cough (when given hot).

7. As a prophylactic against lead poisoning.

8. As a vehicle for the administration of other foods.

9. As a vehicle for the administration of medicines.

10. For rectal injection.

The first three of these uses are so important that they will receive separate detailed consideration (see Diet in. Infancy, page 762, Adaptation of Milk for the Sick, page 74, and Milk Derivatives, page 95; the others may be briefly referred to here.

4. The diuretic action of milk in some persons is very pronounced, while in others it is not noticeable. It is due to the two ingredients, water and lactose or milk sugar. The water acts by increasing the volume of blood and the renal blood pressure. The lactose probably acts directly by stimulating the renal epithelium.

Lactose has been employed with doubtful success as a diuretic - in dropsies and some forms of renal disease. The dose is twenty to thirty grains.

The mineral salts and the water of milk are speedily absorbed by the mucous membrane of the stomach, and in some persons this process is so rapid that milk taken by the tumblerful into an empty stomach has a very decided diuretic effect within an hour. This action may be further promoted by drinking a cup of black coffee.

5. Milk is undoubtedly soothing to the mucous membranes of the alimentary canal. It is often the only variety of food which can be borne by an inflamed or irritable stomach or in some forms of intestinal disease. It is equally soothing in the rectum.

6. A few sips of hot milk or hot milk and Vichy will often allay an irritable cough, and favour the expectoration of tenacious bronchial mucus.

7. Milk is sometimes employed among type founders as prophylactic against lead poisoning. It is claimed by Hirt that if a quart or two be drunk daily, poisoning never occurs.

8. As a vehicle for administration of other foods for invalids, such as egg albumin, beef-meal, meat juice, peptonoids, cocoa, spirits, etc., milk is most useful.

9. As a vehicle for the administration of many medicines and insoluble powders, such as calomel, disagreeable-tasting drugs, like potassium iodide, salicylates, opium, etc., milk is often very serviceable. Sulphonal given in hot milk acts better than if prescribed alone.

10. Milk is employed in nutritive enemata, alone or with beef juice, beef peptonoids, spirits, etc. From one to two or more ounces are given at a time, after cleansing the rectum. A little laudanum may be added, and a towel should be held against the perinaeum to aid in the retention of the milk. When the circumstances admit, it is advisable to pass a long catheter and inject the milk through it as far as the sigmoid flexure, while the patient is supported upon the hands and knees. The higher up the milk is injected, the more readily it is absorbed, and the circulation of the rectum is such, that whatever ingredients of the milk are taken up by the venous capillaries of the lower portion pass to the vena cava, whereas the ingredients absorbed by the superior hemorrhoidal or the sigmoid vessels are carried directly to the vena porta and liver, where they are assimilated more promptly. The lymphatic capillaries also assist in the absorption.

The simple mucous secretions of the rectum have no proper digestive action upon milk (Czerny), but they may sometimes cause putrefaction of its albuminous matter, with formation of tyrosin, indol, etc. (Marckwald). It therefore facilitates absorption to have the milk previously digested by pepsin or pancreatin. Patients having ulcer or carcinoma of the stomach, any intestinal obstruction, or irritant vomiting, may be kept alive for many weeks by the exclusive use of nutrient milk enemata. (See Food Enemata).

Attempts to get milk into the circulation by rubbing it into the skin and by soaking portions of the body in milk baths have proved of no avail, for it is not absorbed in that manner.

The intravenous injection of milk has been occasionally used in cholera collapse, post-partum haemorrhage, etc., and in some few cases it has been found satisfactory, but since saline injections have proved more efficacious, those of milk have been abandoned. Milk has also been injected into the peritoneal cavity, but without much benefit. It has been given hypodermically in doses of four grammes (Menzel). One patient was kept alive sixty-three days in this manner (Whittaker). The milk thus injected is absorbed within an hour.