The new air world

by Willis L. Moore

Carbon dioxide is 1.50 times as dense as an equal volume of atmospheric air. Its greater density causes it to collect in mines, sewers, cellars, and other low places, unless there is forceful ventilation.

The American cold wave should be welcomed as the mighty scavenger of the air. Its high velocity and great density cause it to search into cracks, crevices, sewers, and cellars and expel foul accumulations. How sweet and clean the air smells and how vigorous physically and buoyant mentally one feels after a rain and high winds! All nature smiles and every form of life adds its pæan of joy. Rain washes out the carbonic acid gas (carbon dioxide) from the air, with dust and other particles in suspension; and the cold wave enters our places of habitation and drives out the thieving accumulations of poisonous gases that would rob us of health and maintain conditions of morbidity.

It cannot be too forcefully stated that oxygen, the life-sustaining principle of the air, decreases, and carbon dioxide, a poison, increases in air that is breathed, or in air in which lamps or gas jets are burning; and that all places of habitation, especially sleeping rooms, should have a continuous supply of fresh air.

Water Vapor. It is only a little over one half as dense as atmospheric air. In the arid regions of the west it may form only a fraction of one per cent. of the air by weight; while in the humid regions in the eastern part of the United States it may constitute as much as five per cent. The temperature being the same, the same amount is required to saturate a given space, whether it be a vacuum or whether it be filled with air. Air doubles its capacity for water vapor with each increase of eighteen to twenty degrees. On a hot day in summer, near large bodies of water, it may constitute as much as one twentieth by weight of the lower air, while on a cold day in winter it may form no more than one thousandth part. When the air contains all the water vapor it can hold, it is said to be saturated; no more can be added to it until its temperature is raised, and but a slight lowering of its temperature will precipitate a part of its water vapor in the form of dew, frost, rain, hail, or snow. This is the reason it is usually called water vapor instead of a gas. Under the influence of heat that is below the freezing point, ice and snow may be changed from the solid to the gaseous form, and water vapor may be precipitated as frost or snow without passing through the liquid state.

The Dew Point is the temperature of saturation,—the temperature to which a body of air must be reduced before condensation can occur and some of its water vapor return to the liquid or solid state.

The Relative Humidity is expressed in percentages of the amount necessary to saturate. At a temperature of 32° air may continue to increase its vapor of water until it contains 2.11 grains per cubic foot, when it will be saturated and its relative humidity be one hundred per cent. If this same air be suddenly raised in temperature to 51° its capacity per cubic foot will be increased to twice what it was at 32°, the 2.11 grains will be equal to only one half the number necessary to saturate, and the relative humidity be expressed by fifty per cent. instead of one hundred per cent. In this way does the capacity of air for water vapor increase. Thus it is seen that the relative humidity of the air may increase during the cooling of nighttime without the addition of any vapor of water, and, in fact, with a decrease. The increase of relative humidity after nightfall is greater in the country than in the city, where the presence of pavements and brick buildings retards the loss of heat.

The Absolute Humidity is expressed in grains the cubic foot. The hygrometer is employed to measure the amount of water vapor.

Hydrogen is the lightest of all known gases. Its density in comparison with ordinary air is only .0692. It is combustible, and when five volumes of atmospheric air are mixed with two volumes of hydrogen the mixture explodes when ignited. It is supplied to the air by active volcanoes and in other ways, but the speed of its molecules is such that it readily escapes from the earth’s attraction and passes outward into space.

Ozone (Greek, ozo, I smell) is highly electrified oxygen, in which the molecules are broken up and reformed so as to contain additional atoms. It is formed by the disruptive discharge of lightning and by the great amount of electricity present in the high levels of the atmosphere, and possibly in minute quantities by the evaporation of fog and water near the earth. It is always found in the presence of waterfalls and spraying fountains. It is a powerful sanitary agent, readily entering into union with decaying matter. This fact accounts for the total absence of ozone from the air of large cities.

Ozone, in the minute quantities found in nature, is healthful, but when breathed in a condensed form it has a highly irritating effect on the mucous surfaces of the respiratory passages, and the quantity is not large that will cause death. The healthfulness of mountain air may be due largely to the increase with elevation in the quantity of ozone and electricity in the air, as well as to the less number of disease germs and dust motes. The invigorating effects of the crisp air of the frosty morning and of the cold wave in winter may be increased by the activities of ozone.