Prep. The milk is coagulated, the curd separated, and after the whey has been evaporated to the crystallizing point, pieces of wood or cord are introduced, upon which the milk sugar crystallizes.

Prop. & Comp. Milk sugar occurs in cylindrical masses, about 2 inches in diameter and several inches in length, having an axis of cord or wood: the masses are composed of crystals, grayish white, translucent and hard; without odour, and with a slightly sweet taste; it is gritty in the mouth from the slight solubility of the sugar in the saliva. Milk sugar consists of a crystalline principle, termed Lactin or Lactose, which has the composition (C24 H24 O24); or it may be represented by the formula (C24 H19 O19 + 5 HO), the water in the compound being capable of replacement by oxide of lead. Lactose can be obtained in 4-sided prisms, terminated by 4-sided pyramids; it is soluble in about 6 times its weight of water, the solution is much less sweet than that of cane sugar; it is not soluble in alcohol or ether. It is not subject to alcoholic fermentation, but milk is so from the prior slow conversion of the lactose into glucose. When milk ferments in contact with chalk, lactic acid is formed.

Therapeutics. It may be employed for the purpose of rubbing up powerful medicinal powders, as white bismuth, calomel, 25 hydrochlorate of morphia, etc. Its action as a remedy is not readily appreciable. Probably milk sugar might be advantageously employed as a substitute for cane sugar in the diet of infants. Cow's milk diluted with water, with the addition of milk sugar, forms a good substitute for the milk of the human female.

Dose. Ad libitum.