When it is taken into account that the lungs of an average sized man contain upwards of six hundred millions of minute air cells, the surface area of which represents many thousands of square feet, the danger of exposing such a vast area of delicate tissue to the action of vitiated air can be readily estimated. No matter how nutritious the food may be that is taken into the stomach, no matter how perfect the processes of digestion and assimilation are, the blood cannot be vitalized without fresh air. It is estimated that the blood is pumped through the lungs at the rate of eight hundred quarts per hour, and that during that period it rids itself of about thirty quarts of carbonic acid gas, and absorbs about the same amount of oxygen. Think for a moment of the madness of obstructing this interchange of elements which is perpetually going on and on which life depends! It is more especially during the hours of sleep that fresh, pure air is needed, for that is when Nature is busiest, repairing and building up, and calls for larger supplies of oxygen to keep up the internal fires, but her efforts at repairing waste are rendered futile if you diminish the supply of the vitalizing element and compel her to use over again the refuse material she has already cast off. The late Prof. Willard Parker, in a lecture delivered before a class of medical students, made a very forcible illustration of how the air of a room was vitiated, in the following impressive words: "If, gentlemen, instead of air you suppose this room filled with pure, clean water, and that instead of air you were exhaling twenty times a minute a pint of milk, you can see how soon the water, at first clear and sparkling, would become hazy and finally opaque; the milk diffusing itself rapidly through the water, you will thus be able, also, to appreciate how, at each fresh inspiration you would be taking in a liquid that grew momentarily more impure. Were we able to see the air as we see the water, we would at once appreciate how thoroughly we are contaminating it, and that unless there be some vent for the air thus vitiated, and some opening large enough to admit a pure supply of this very valuable material, we will be momentarily poisoning ourselves, as surely as if we were taking sewage matter into our stomachs." Don't leave the matter of a good supply of air to servants. See to it yourself and see that you are not robbed of it. It would be better to trust your eating to an attendant than your breathing. Do that yourself.