_Observations._ 1st. Many persons have died from breathing carbonic acid that was formed by burning charcoal in an open pan or portable furnace, for the purpose of warming their, sleeping-rooms. This is not only produced by burning charcoal, but is evolved from the live coals of a wood fire; and being heavier than air, it settles on the floor of the room; and, if there is no open door or chimney-draught, it will accumulate, and, rising above the head of an individual, will cause asphyxia or death. 2d. In resuscitating persons apparently dead from causes already mentioned, if a pair of bellows cannot be procured immediately, let their lungs be inflated by air expelled from the lungs of some person present. To have the expired air as pure as possible, the person should quickly inflate his lungs, and instantly expel the air into those of the asphyxiated person. _Place the patient in pure air, admit attendants only into the apartment, and send for a physician without delay._ -=-=-=-=-=-=-=-=-=-=-=-= What sad results frequently follow the burning of charcoal in a closed room? What suggestion in resuscitating asphyxiated persons? -=-=-=-=-=-=-=-=-=-=-=-= CHAPTER XXVII. ANIMAL HEAT. 545. The true sources of animal heat, or calorification, are still imperfectly known. No hypothesis has, as yet, received the concurrent assent of physiologists. We see certain phenomena, but the ultimate causes are hidden from our view. Its regular production, to a certain degree, is essential both to animal and vegetable life. 546. There is a tendency between bodies of different temperature to an equilibrium of heat. Thus, if we touch or approach a hot body, the heat, or caloric passes from that body to our organs of feeling, and gives the sensation of heat. On the contrary, when we touch a cold body, the heat passes from the hand to that body, and causes a sensation of cold. 547. The greater number of animals appear cold when we touch them; and, indeed, the temperature of their bodies is not much above that of the atmosphere, and changes with it. In man, and other animals that approach him in their organization, it is otherwise. They have the faculty of producing a sufficient quantity of caloric to maintain their temperatures nearly at the same degree, under all atmospheric changes, and keep themselves warm. 548. Those animals whose proper heat is not very perceivable, are called _cold_-blooded; as most species of fishes, toads, snakes, turtles, and reptiles generally. Those animals which produce sufficient heat independently of the atmosphere surrounding them, are called _warm_-blooded; as man, birds, quadrupeds, &c. -=-=-=-=-=-=-=-=-=-=-=-=