Health is maintained by a vitalizing triad: air, light and food, which constitute the necessary elements of nutrition. So life depends on the earth and its atmosphere, and human nature, therefore, is inseparably linked with, and under the influence of, the numerous atmospheric conditions that surround us.
Air, as we believe, is a mixture of about 21 parts of oxygen and 79 of nitrogen, more or less saturated with water vapors. The nature and amount of these vapors depend on various circumstances, such as proximity to the sea, bodies of fresh water, the existence of winds, altitude, etc.
Air contains a certain quantity of ozone, "a sort of electricized or condensed oxygez," fatal to miasmatic and decomposition developments. Ozone is scarce in the air of cities, but renewed at intervals everywhere, in a measure, by electric phenomena, as all of us have noted in the peculiar freshness—almost pungency—of the air