“The escape of offensive matter from the body becomes most obvious when, from out of the pure air in the morning, one enters an unventilated bedroom where one or two have slept the night before. Every one must have experienced the sickening and disgusting odor upon going into such a room, though its occupants themselves do not recognize it. The nose, although an organ of excessive sensibility, and capable of perceiving the presence of offensive matters where the most delicate chemical tests fail, is nevertheless easily blunted, and what at the first impression is pre-eminently disgusting, quickly becomes less offensive to the smell; but the impure air has not departed. Two persons, occupying a bed for eight hours, impart to the sheets by insensible perspiration, and to the air by breathing, a pound of watery vapor charged with latent animal poison. When the air in other inhabited rooms is not often changed, the water of exhalation, thus loaded with impurities, condenses upon the furniture, windows, and walls, dampening their surfaces, and running down in unwholesome streams. “Yet we are not to regard the human body as necessarily impure, or a focus of repulsive emanations. It is not by the natural and necessary working of the vital machinery that the air is poisoned, but by its artificial confinement, and the accumulation of deleterious substances.” In speaking of the prevalent inattention to a perfect ventilation in our homes, and the need of great care in this respect, if we would secure health, Youmans also refers to the “gaseous exhalations, of every sort, that escape from our kitchens, filling the house with unpleasant odors; the imperfect combustion of oil and tallow in lighting our homes; the defective burning of gas-jets”; and the injurious effects upon health,--causing severe headaches, if nothing worse; to the destruction to health from the poisonous influences of green paper-hangings upon the air, from which the fine particles, loosened by dusting or moving about the room, are set afloat in the atmosphere, and are often very deadly. Then from the decayed vegetables--carelessly allowed to remain sometimes for days in our cellars--and the damp and stagnant air of cellars and basements come exhalations most destructive to health. Even dry closets and rooms in upper stories become moldy and musty if not often and thoroughly aired. “To be pure and healthy, air requires continual circulation; but cellars are rarely either ventilated or made dry by water-proof walls or floors, and are usually damp, cold, unclean, and moldy. “The air from these basements and cellars ascends to the upper rooms in such small quantities that it does not produce immediate disease; yet it so gradually undermines the health as not to be perceptible. Many an invalid, who fancies himself benefited by the change of air in going to another residence, is really only improved by escaping the moldy atmosphere that arises from beneath his own ground-floor.”