In each of these experiments, the cylinder was covered with condensed watry vapor exactly in the same manner as if common air had been breathed in it. It ought to be observed that, E. 1. was made in the morning, four hours and half after a moderate breakfast; whereas, E. 2. was made but an hour and quarter after a plentiful dinner; at which near three fourths of a pint of table-beer had been drank. From these experiments we learn, that nitrous oxide is rapidly absorbed by the venous blood, through the moist coats of the pulmonary veins. But as after a compleat voluntary exhaustion of the lungs, much residual air must remain in the bronchial vessels and fauces, as appears from their incapability of compleatly collapsing, it is evident that the gas expired after every inspiration of nitrous oxide mast be mingled with different quantities of the residual gas of the lungs;[192] whilst after a complete expiration, much of the unabsorbed nitrous oxide must remain as residual gas in the lungs. Now when a complete expiration is made after the breathing of atmospheric air, it is evident that the residual gas of the lungs consists of nitrogene,[193] mingled with small portions of oxygene and carbonic acid. And these are the only products found after the respiration of nitrous oxide. [192] By lungs, I mean in this place, all the internal organs of respiration. [193] Because these products are formed during the respiration of common air. To ascertain whether these products were partially produced, during the process of respiration, as I was inclined to believe from the experiments in the last section, or whether they were wholly the residual gases of the lungs, I found extremely difficult. I at first thought of breathing nitrous oxide immediately after my lungs had been filled with oxygene; and to compare the products remaining after the full expiration, with those produced after a full expiration of pure oxygene; but on the supposition that oxygene and nitrous oxide, when applied together to the venous blood, must effect changes in it different from either of them separately, the idea was relinquished. I attempted to inspire nitrous oxide, after having made two inspirations and a complete expiration of hydrogene; but in this experiment the effects of the hydrogene were so debilitating, and the consequent stimulation by the nitrous oxide so great, as to deprive me of sense. After the first three inspirations, I lost all power of standing, and fell on my back, carrying in my lips the mouth-piece separated from the cylinder, to the great alarm of Mr. Patrick Dwyer, who was noting the periods of inspiration.