The bottles should be rinsed with cold water after each feeding and then carefully washed and scrubbed with the bottle brush in hot soapsuds or borax water, containing two tablespoonfuls to the pint. They may be kept full of water while not in use or rinsed with hot water and stood upside down until they are all boiled on the following morning, preparatory to being filled with the freshly prepared milk. The baby’s bottles should never be washed in dishwater nor dried on a towel. The nipples should be rinsed in cold water, turned inside out and scrubbed with a brush, in hot soapsuds or borax water; rinsed and placed in a jar ready to be boiled with the bottles. =Preparing the Milk.= The full quantity of milk which the baby will take in the course of twenty-four hours is prepared at one time and the prescribed amount for each feeding poured into as many separate bottles as there will be feedings. You should begin by assembling on a table everything that you will use in preparing the milk formula, as the nurse has in Fig. 47. Boil for five minutes all of the articles that will come in contact with the milk, including the full number of bottles and nipples and the jars in which the nipples are kept; remove them with the long-handled spoon without touching the edges or inner surfaces, dropping the nipples into one of the sterile jars. Wash the mouth of the milk bottle before removing the cap and pour the amount which the formula calls for into the sterile pitcher. To this is added the sterile water in which the sugar has been dissolved in the measuring glass and then the potato or barley water, the lime water or soda solution as ordered. This mixture is thoroughly stirred and the amount for one feeding at a time, measured in the measuring glass and poured into the specified number of bottles, which are then stoppered. [Illustration: FIG. 47.—Preparing the baby’s milk. (From a photograph taken at Johns Hopkins Hospital.) ] If certified milk is used for the milk mixture it is often given to the baby without being pasteurized, in which case the bottles are placed in the refrigerator as soon as they are filled and stoppered. Very frequently, however, the milk is sterilized or pasteurized. You will feel surer of keeping the mouths of the bottles clean if you cover them with squares of gauze or muslin before they are sterilized, holding the caps in place with tapes or rubber bands. Pasteurization as applied to infant feeding consists of heating the milk to 140–165° F. and keeping it at that temperature for 20 to 30 minutes.