Soil has air in it. Sometimes it is good air, sometimes bad air. The soil newly turned up in the fields gives off a fragrance of its own. The earth thrown out on the city pavement by a man looking for a leak in a drain gives off an odour which makes one hurry one's steps. The soil under a house gives off vapours and gases in the same way, good or bad according to location. Inasmuch as we cannot watch the air under the house as we can that in a room and would not always know its quality if we could, it has been found better to dig out a chamber under the house and line it with stones or cement, or even leave it just a hole in the earth into which air can be admitted. For this allows a circulation of upper air under the house which is safer to have there than air from the soil. The more we can shut out the breath of the soil in towns and cities the better, for such soil is full of drains and gas pipes, and the dirt of streets and crowded houses, and sometimes has buried in it cess-pools and leaking sewers. Unpleasant to think of? Yes, but the thought does very well as a spur to make one keep the cellar clean and dry. A cellar sealed with cement is the best kind, because the soil-air is shut out unless there comes a crack in the cement. Walls of stone laid in cement are good but not so good, and brick walls are not nearly so good. Stones are a little porous and bricks very porous. Sooner or later moisture comes through either. In the country one often sees cellars with hard earth floors and they are fairly sanitary as long as the soil surrounding the house is used only for cleanly purposes. But before plumbing is put into the house or a sewer into the neighbourhood the cellar should be cemented. I have seen cellar windows which would not open. They ought to open easily and one at least should be opened for a while every day that it is not snowing or raining. They ought also, to be kept as clean as other windows are, for light is necessary to the healthfulness of the cellar. Have the window openings covered with wire netting, strong enough on the one hand and fine enough on the other to exclude cats and flies. Every cellar without any exception whatever should be white. White! They may be painted white or whitewashed white. There are also substances of the nature of calcimine which are somewhat crystalline, and are therefore especially good for whitening dark cellars. Whitewash is often decried because it rubs off upon things which touch it and also because flakes of it fall upon the floor and into uncovered receptacles. If a little size or thin glue is put into whitewash its objectionableness in these ways is much lessened, and comes to weigh little against its excellent recommendations; it is purifying, it destroys the eggs of insects, it is inexpensive and it requires no special skill to apply it. There are a few words on this last point in the chapter on housecleaning.