rld of mechanical transposition and the world of chemical tra

ing bodies, and the whole panorama of our material civilization; the latter is the world of silent, invisible, unsleeping, and all-potent chemical

echanico-vital, act; the mechanical principle involved is the same as that involved in the working of a bellows, but the oxidation of the blood when the air enters the lungs is a chemical act, or a chemico-vital act. The air gives up a part of i

es with other substances very reluctantly and with but little energy. Oxygen is just its opposite in this respect: it gives itself freely; it is "Hail, fellow; well met!" with most substances, and it enters into co-partnership with them on such a large scale that it forms nearly one half of the material of the earth's crust. This invisible gas, this breath of air, through the magic of chemical combination, forms nearly half the substance of the solid rocks. Deprive it of its affinity for carbon,

t of our experiences with tangible bodies. In the visible, mechanical world no two bodies can occupy the same place at the same time, but apparently in chemistry they can and do. An atom of oxygen and one of carbon, or of hydrogen, unite and are lost in each other; it is a marriage wherein the two or three become one. In dealing with the molecules and atoms of matter we are in a world wherein the laws of solid bodies do not apply; friction is abolished, elasticity is perfect, and place and form play no part. We have escaped from matter as we know it, the solid, fluid, or gaseous forms, and are dealing with it in its fourth or ethereal estate. In breathing

all, that breathing is only to a very limited extent a voluntary act. It is controlled by muscular machinery, but that machinery would not act in a vacuum. We contract the diaphragm, or the diaphragm contracts under stimuli received through the medulla oblongata from those parts of the body which constantly demand oxygen, and a vacuum tends to form in the chest, which is constantly prevented by the air rushing in to fill it. The expansive force of the air under its own weight causes the lungs to fill, just as it causes the bel

e other. Indeed, it seems to me that next to the mystery of life is the mystery of fire. The oxidizing processes are identical, only one is a building up or integrating process, and the other is a pulling down or disintegrating process. More than that, we can evoke fire any time, by both mechanical and chemical means, from the combustible matter about us; but we cannot evoke life. The equivalents of life do not slumber in our tools as do the equivalents of fire.