~Technique of Milk Modification.~--The absolute necessity for cleanliness has already been dwelt upon in respect to milk, and in infant feeding the vigilance which must be observed in the preparation of the food cannot be too strongly emphasized. The milk itself must be of known purity. Where there is any uncertainty about its source, it must be sterilized or pasteurized according to the doctor's orders. The bottles and nipples should be washed as soon as they are used, first with plain water to remove the milk, then with soapsuds and a bottle brush. The bottles should then be filled with boric acid or bicarbonate of soda solution until needed, when they should be emptied and placed in a deep pan filled with cold water and allowed to boil for a few minutes. They should not be taken from the water until they are to be filled with the milk mixture. The nipples are washed thoroughly and boiled once a day and dropped into a solution of boric acid or bicarbonate of soda when not in use. The plain black rubber nipples are best as they can easily be turned inside out and cleaned. If the milk drops too slowly from the bottle, the nipple may be pierced in one or two places with a darning needle. The morning is the best time in which to prepare the baby's food; the milk has not stood too long and it is easier to regulate the feedings if a fresh start is made each morning. Let the bottles and the rubber corks with which they must be stopped be boiled and cooled while the milk mixture is being prepared. ~Preparation of Diluents.~--If barley or oatmeal water is to be used as a diluent, let that be prepared first, that it may be cool before adding it to the milk. Cover the table with a clean cloth or oilcloth, upon this place the pitcher in which the milk is to be modified, have the funnel, milk dipper, and spoon which are to be used boiled with the bottles, cover the mouth of the pitcher with a clean square of gauze or cheesecloth, read the formula carefully and measure the sugar, dextri-maltose, lactose, Mellin's Food, or cane sugar as directed and place it in a clean glass; now measure the diluent, water, oatmeal water, barley water, or whey; use part of this diluent to dissolve the sugar. ~Measuring Milk according to Percentage of Fat.~--Now dip off the required layer of top milk, that is, the layer containing the desired percentage of fat and protein. Mix this thoroughly and dip out the requisite number of ounces into the pitcher. If there is not sufficient cream in one quart bottle to fill the formula, the cream must be dipped from a second bottle and mixed with that of the first before it is measured into the pitcher. The dissolved sugar and rest of the diluent, together with the correct amount of limewater, are strained into the pitcher, mixed thoroughly, and strained through the absorbent cotton lining the funnel into the bottles, allowing the correct number of ounces for each feeding in every bottle.