When milk is administered to those whose digestive organs are weak and incapable of full work, it is often partly digested beforehand. This is accomplished by adding to milk that has been slightly acidified a good preparation of pepsin. The mixture is kept at body-temperature by immersion in hot water. The proteins of the milk are soon converted into albu-moses. If digestion is allowed to continue, the mixture becomes bitter. It is customary, therefore, to remove the milk from the hot water before it grows bitter and to place it upon ice until it is used. Pancreatin is employed more often than pepsin for the digestion of milk, for it acts in an alkaline medium. A small amount of pancreatic extract and a few grains of sodium bicarbonate are dissolved in water and added to the milk.

The mixture is kept at body-temperature or slightly higher, usually by placing the containing vessel in water at from 100° to 110° F. for about fifteen or twenty minutes until a slightly bitter taste is developed. The ferment is then destroyed by quickly bringing the milk to a boil and afterward placing it upon ice; or it may be placed upon ice without the preliminary boiling, in which case the activity of the ferment will be checked, but not destroyed. In what is termed the cold process, the digestive powder is dissolved in water added to the milk, and the whole placed upon ice, or allowed to stand, properly covered, in a cool room and used as wanted. Fair-child's tubes of peptonizing powder are composed of pancreatic extract five grains and sodium bicarbonate fifteen grains. One of these tubes will digest a pint of milk. There are various other good preparations upon the market. To prevent curdling of the milk by the digestive powder it is necessary to dissolve the latter in a sufficient quantity of water - about one-fourth the bulk of the milk to be prepared. This holds good for all methods of preparation. Milk that is predigested in these ways should be taken cold. Its bitter taste may be disguised by the addition of a little coffee or carbonized water. The taste of the digested milk can also be well disguised by mixing together equal parts of milk and of flour gruel before the pancreatic powder is added. In many cases it will suffice to dissolve the necessary quantity of peptonizing powder in sufficient cold water, stir this into warm milk, and give to the patient at once, before the bitter taste develops. Milk thus prepared is sometimes termed 'pancreatized milk,' to distinguish it from the peptonized milk that has been allowed to stand. It is rare for a patient to object to the taste.

To make milk more digestible for certain persons, and especially for infants, its components are modified in their proportions by diluting it with water and by adding, if need be, cream and milk-sugar. Such milk modification or the preparation of percentage milk is described as a part of infant feeding in a subsequent chapter.

Kumiss is a milk preparation that is agreeable to many patients, very readily digested, and more completely absorbed than ordinary milk. It has been made for many hundred years in Eastern Europe from mare's milk. A substitute for it, made from cow's milk, is called kephyr.1 All so-called kumiss in this country is kephyr. The presence of more fat in cow's milk than in mare's milk makes it less suitable for the fermentation that must take place to convert it into kephyr; therefore it is diluted or modified before it is fermented. The ferments used effect several changes in the milk. A part of the sugar in it is converted into lactic acid; another part into alcohol and carbonic acid gas, and a small amount of the casein is digested. The lactic acid precipitates the casein in fine particles; by constant agitation they are made still finer and gradually undergo partial digestion. The product is a milk that is sour, effervescent, and weakly alcoholic. The following table from Hutchison gives

1 Kephyr, like kumiss, was first made in the Caucasus by fermenting cow's milk with saccharomyces mycoderma, which produces alcohol, and lactic-acid-forming organisms. The kephyr granules used in the Caucasus to start this fermentation contain also bacterium dispora caucasica. It was supposed this played a part in producing the beverage - kephyr - but recent investigations show that it produces little or no effect. It may help to liquefy the precipitated casein.

According to C D. Spivak (" N. Y. Medical Journal," Jan. 18, 1896, p. 82): " The Tartars prepare the kephyr in the following manner: A leathern bag (burdjuck) is filled with fresh cow's or goat's milk, the kephyr grains are thrown in, and the bag is tightly tied up. In summer the bag is placed in the shade, and in winter where the sun can reach it. From time to time the bag is shaken. The children take the office upon themselves, and usually the bag is used as a ball. It is also considered a duty that every passer-by should kick the bag, and set it rolling. In a few hours, or, at the utmost, two days - according to the season - the kephyr is ready for use. The bag is emptied and refilled, using the same grains over and over again.

"The method of preparation now used in civilized countries is that elaborated by Dr. Dmitriefl. The grains are placed in an earthern or darkened glass vessel and are covered with milk, the bulk being three times that of the grains. The mouth of the vessel is covered with gauze or hygroscopic cotton with a view to exclude the ingress of dust only, and not to make it air-tight. The vessel is placed in a cool place at 120 R., and as soon as the fermentation sets in - i.e., as soon as the grains rise to the surface of the milk - the vessel is to be shaken up every two or three hours, with a view to thoroughly mixing up the fluid and liberating the grains from the curds and the bubbles. After twenty-four hours the grains are separated from the fluid by means of a sieve, are placed in a clean vessel, and a new quantity of milk is poured on them. Unlike the Tartar method, this product is not used as a beverage, but as a fermenter,' or, as it is called in Russia, 'zakvaska.' The zakvaska is diluted with double the quantity of milk and poured into bottles, which are corked hermetically. The bottles must not be completely filled, as they may burst. They are kept at the same temperature as the zakvaska, but they do not require the exclusion of light. The shaking is to continue at regular intervals, but not so that it may churn the milk. In twenty-four hours the kephyr is ready for use, and it is called the first day's kephyr, or weak kephyr. It has the following characteristics: the consistence of thin, sour cream, a white color, a pleasant, sour-sweetish taste, slightly acrid. When the bottle is opened it effervesces. The walls of the bottle and the glass which have held kephyr are covered with fine curds. When the bottle is left under the same conditions for another twenty-four hours, the kephyr is called second day's or medium kephyr; in forty-eight hours, third day's or strong kephyr. The terms weak, medium, and strong kephyr refer to the quantity of alcohol and carbonic acid gas contained in it."

The relative composition of kumiss and mare's milk, of kephyr and cow's milk, and compares them with each other:

When kumiss or kephyr is fermented for only twelve hours, it is slightly sour and resembles milk in taste and appearance; when fermented for twenty-four hours, some of the casein will be dissolved, and the kumiss will be thinner and sourer. If the process is continued another day, it will be still thinner, sourer, and more thoroughly charged with carbonic acid gas.

In Russia there are many places where the kumiss cure is applied. Those who need the cure are placed in sanatoriums, taught to drink large quantities of kumiss, and also fed generously of other foods. The change of climate, the influence of the sun, and the fesh-air life have much to do with the cures that are effected at these resorts. At first, four or five glasses of kumiss are given daily. By degrees more is given, until from fifteen to twenty are taken in a day. It is especially valuable in some chronic catarrhs of the alimentary and respiratory tracts, the early stage of pulmonary tuberculosis, anemia, scrofula, and rachitis. It is certainly nutritious and distinctly diuretic. If kumiss is too fresh or has not been kept clean, it may cause flatulence, colic, and diarrhea. It is often used as a substitute for milk by those who prefer its taste.

Matzoon is a fermented milk. A lactic acid ferment obtained from Syria is used in its manufacture. It is sour, thicker, and is more of the consistency of cream than kumiss. It does not contain alcohol or carbonic acid gas, and is taken in smaller amounts at a time. It is agreeable, very readily digested, and also highly nutritious.