2.  Dirty air coming from within, from dust, which you often displace, but never remove.  And this recalls what ought to be a sine qua non.  Have as few ledges in your room or ward as possible.  And under no pretence have any ledge whatever out of sight.  Dust accumulates there, and will never be wiped off.  This is a certain way to soil the air.  Besides this, the animal exhalations from your inmates saturate your furniture.  And if you never clean your furniture properly, how can your rooms or wards be anything but musty?  Ventilate as you please, the rooms will never be sweet.  Besides this, there is a constant degradation, as it is called, taking place from everything except polished or glazed articles—­E.g., in colouring certain green papers arsenic is used.  Now in the very dust even, which is lying about in rooms hung with this kind of green paper, arsenic has been distinctly detected.  You see your dust is anything but harmless; yet you will let such dust lie about your ledges for months, your rooms for ever.

Again, the fire fills the room with coal-dust.

[Sidenote:  Dirty air from the carpet.]

3.  Dirty air coming from the carpet.  Above all, take care of the carpets, that the animal dirt left there by the feet of visitors does not stay there.  Floors, unless the grain is filled up and polished, are just as bad.  The smell from the floor of a school-room or ward, when any moisture brings out the organic matter by which it is saturated, might alone be enough to warn us of the mischief that is going on.

[Sidenote:  Remedies.]

The outer air, then, can only be kept clean by sanitary improvements, and by consuming smoke.  The expense in soap, which this single improvement would save, is quite incalculable.

The inside air can only be kept clean by excessive care in the ways mentioned above—­to rid the walls, carpets, furniture, ledges, &c., of the organic matter and dust—­dust consisting greatly of this organic matter—­with which they become saturated, and which is what really makes the room musty.

Without cleanliness, you cannot have all the effect of ventilation; without ventilation, you can have no thorough cleanliness.

Very few people, be they of what class they may, have any idea of the exquisite cleanliness required in the sick-room.  For much of what I have said applies less to the hospital than to the private sick-room.  The smoky chimney, the dusty furniture, the utensils emptied but once a day, often keep the air of the sick constantly dirty in the best private houses.

The well have a curious habit of forgetting that what is to them but a trifling inconvenience, to be patiently “put up” with, is to the sick a source of suffering, delaying recovery, if not actually hastening death.  The well are scarcely ever more than eight hours, at most, in the same room.  Some change they can always make, if only for a few minutes.  Even during the supposed eight hours, they can change their posture or their position in the room.  But the sick man, who never leaves his bed, who cannot change by any movement of his own his air, or his light, or his warmth; who cannot obtain quiet, or get out of the smoke, or the smell, or the dust; he is really poisoned or depressed by what is to you the merest trifle.