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The oxygen of the atmosphere, and only it, is the vivifying element. In effect, while the confinement in the pure oxygen preserves the life for large space, on the contrary close any animal tightly in a vase full of air; past certain time, it will perish suffocated; analyze the air of the vase, and the oxygen will be missed. The same death will be the necessary consequence of the lingering inhalation of the nitrogen, as of the carbonic acid. This demonstrated consumption of the oxygen in the breathing work is not an isolated phenomenon, follows it in linked proportion, position that susceptible of variations, the production of carbonic acid and aqueous vapors, besides the consumption and production of the nitrogen in very tiny amount. The same demonstrative experience of the consumption of the oxygen proves the sequent production of carbonic acid and vapors of water, because that not only it is noticed the decrease of that, as it is discovered the increase of these. Experiences of the same order confirm of equal it supplies the absorption and exhalation of the nitrogen. It is here that fits to meditate that, bad will the deleterious action of the carbonic acid, and the inertia of the nitrogen, they are them with everything useful and even necessary to the life, for that that, mixed to the oxygen in the proportions of the atmosphere, they reduce the force ultra-stimulant of the oxygen, by which, alone, it would come to destroy the whole organization, determining the combustion of all the tissues. Still that is for the experience confirmed, therefore that in this case, the one of the breathing in the pure oxygen, as Allen and Pepys noticed, the amount of the exhaled carbonic acid is much larger, and according to the calculations of Liebig, in short time the oxygen would put an end to all the carbon of the economy, not being this renewed. Of this brief, but exact exposition it is concluded that of the breathing it results for the atmospheric air alterations in the amount of its principles, winning in two and losing in one. In convenient place it will be fastened with very approximate accuracy the quantum of the lost oxygen, as well as of the acquired carbonic acid.

Modifications of the blood.

Attending to the proven alterations of the atmospheric air in the act of the breathing, coming alterations of your fight with the nutritious fluid, the blood, at once is inferred that must this ipso facto suffer modifications; and actually it suffers them, not only in the proportions of its essential chemical elements, that is, the carbon and the hydrogen, whose amount decreases, and the nitrogen and the oxygen, that increase, especially the last, but also in your physical characters, and still more in its physiologic properties. Its dark red color is made rutilant-red, its temperature rises degree and half, as it demonstrates the F. thermometer; finally, from unable to feed and of noxious even, the blood becomes vivifying and apt to being assimilated. It is then that sent of the heart