Liebig, the great chemist, asserts that a small quantity of table salt to the food is essential to the health of children. The milk itself ought not to be heated over the fire, but should, as above directed, be warmed by the water; it must, morning and evening, be had fresh and fresh. It now and then happens that if the milk be not boiled, the motions of an infant are offensive; _when such is the case_ let the milk be boiled, but not otherwise. The milk and water should be of the same temperature as the mother’s milk, that is to say, at about ninety to ninety-five degrees Fahrenheit. It ought to be given by means of a feeding-bottle, and care must be taken to _scald_ the bottle out twice a day, for if attention be not paid to this point the delicate stomach of an infant is soon disordered. As he grows older the milk should be gradually increased, and the water decreased, until nearly all milk be given. There will, in many cases, be quite sufficient nourishment in the above; I have known some robust infants brought up on it alone. But if it should not agree with the child, or if there should not be sufficient nourishment in it, then the food recommended in answer to No. 34 question ought to be given, with this only difference—a little new milk _must_ from the beginning be added, and should be gradually increased, until nearly all milk be used. The milk, as a general rule, ought to be _unboiled_; but if it purge violently, or if it cause offensive motions—which it sometimes does—then it must be boiled. The moment the milk boils up it should be taken off the fire. Food ought, for the first month, to be given about every two hours; for the second month, about every three hours; lengthening the space of time as the baby advances in age. A mother must be careful not to over-feed a child, as over-feeding is a prolific source of disease. Let it be thoroughly understood, and let there be no mistake about it, that a babe, during the first nine months of his life, MUST have—it is absolutely necessary for his very existence—milk of some kind, as the staple and principal article of his diet, either mother’s, or wet-nurse’s, or asses’, or goat’s, or cow’s own milk. 37. _How would you choose a wet-nurse?_