One of the strongest objections to open stoves and fire-places in the nursery is, the increased exposure to accidents. I know it is said that this evil may be avoided by laying aside the use of cotton, and wearing nothing but worsted or flannel. This is indeed true; but I do not like the idea of being compelled to dress children in flannel or worsted, at all times when the least particle of fire is demanded; for this would be to wear this stimulating kind of clothing, in our climate, the greater part of the year. Besides, I write for many mothers who are compelled to use cotton, on account of the expense of flannel. And if the stove be a close one, and well defended by a railing, cotton will seldom expose to danger. Still, as has been already said, the introduction of heated air from another apartment, whenever it can possibly be afforded, is incomparably better than either stoves or fire-places. Dr. Dewees is fully persuaded that the excessive heat of nurseries has occasioned a great mortality among very young children. "In the first place," he says, "it over-stimulates them; and in the second, it renders them so susceptible of cold, that any draught of cold air endangers their lives. They are in a constant perspiration, which is frequently checked by an exposure to even an atmosphere of moderate temperature." If this is but to repeat what has been already said, the importance of the subject seems to be a sufficient apology. CHAPTER III. VENTILATION. General ignorance of the constitution of the atmosphere. The subject briefly explained. Oxygen gas. Nitrogen. Carbonic acid. Fires, candles, and breathing dependent on oxygen. Danger from carbonic acid. How it destroys people. Impurity of the air by means of lamps and candles. Other sources of impurity. Experiment of putting the candle under the bed-clothes. Covering the heads of infants while sleeping--its dangers. Proportions of oxygen and nitrogen in pure and impure air. No wonder children become sickly. Particular means of ventilating rooms. Caution in regard to lamps. Washing, ironing, cooking, &c., in a nursery. Their evil tendency. Fumigation--camphor, vinegar. Few people take sufficient pains to preserve the air in any of their apartments pure; for few know what the constitution of our atmosphere is, and in how many ways and with what ease it is rendered impure.