The close connection between ventilation and cleanliness is shown in this. An ordinary light paper will last clean much longer if there is an Arnott's ventilator in the chimney than it otherwise would.
The best wall now extant is oil paint. From this you can wash the animal exuviæ.[30]
These are what make a room musty.
Best kind of wall for a sick-room.
The best wall for a sick-room or ward that could be made is pure white non-absorbent cement or glass, or glazed tiles, if they were made sightly enough.
Air can be soiled just like water. If you blow into water you will soil it with the animal matter from your breath. So it is with air. Air is always soiled in a room where walls and carpets are saturated with animal exhalations.
Want of cleanliness, then, in rooms and wards, which you have to guard against, may arise in three ways.
Dirty air from without.
1. Dirty air coming in from without, soiled by sewer emanations, the evaporation from dirty streets, smoke, bits of unburnt fuel, bits of straw, bits of horse dung.
Best kind of wall for a house.