air every hour. The membrane that lines the multitudinous air-cells
of the lungs in which the capillaries are, should it be united in one
sheet, would cover the floor of a room twelve feet square. Every breath
brings a surface of air in contact with this extent of capillaries,
by which the air inspired gives up most of its oxygen and receives
carbonic acid in its stead. These facts furnish a guide for the proper
ventilation of rooms. Just in proportion to the number of persons in
a room or a house, should be the amount of air brought in and carried
out by arrangements for ventilation. But how rarely is this rule
regarded in building houses or in the care of families by housekeepers!

The evils resulting from the substitution of stoves instead of the
open fireplace, have led scientific and benevolent men to contrive
various modes of supplying pure air to both public and private houses.
But as yet little has been accomplished, except for a few of the more
intelligent and wealthy. The great majority of the American people,
owing to sheer ignorance, are, for want of pure air, being poisoned
and starved; the result being weakened constitutions, frequent disease,
and shortened life.

Whenever a family-room is heated by an open fire, it is duly ventilated,
as the impure air is constantly passing off through the chimney, while,
to supply the vacated space, the pure air presses in through the cracks
of doors, windows, and floors. No such supply is gained for rooms
warmed by stoves. And yet, from mistaken motives of economy, as well
as from ignorance of the resulting evils, multitudes of householders
are thus destroying health and shortening life, especially in regard
to women and children who spend most of their time within-doors.

The most successful modes of making "a healthful home" by a full supply