Painting wood or iron-work is valuable, not only as a preservative from the effects of the weather and the oxidising action of the air, but also because it tends, to a large extent, to prevent the absorption of organic matters; and its surface can be frequently cleansed. =Paper= is the material most commonly employed for covering walls. It is more absorbent and retentive of moisture than distemper. Light-coloured papers should be chosen, as they are more cheerful, and are not so likely to harbour dust. Glaring patterns are objectionable, as they tire the eyes. The paper should not present any surface-projection for the lodgment of dust. In bathrooms and water-closets, the wall-surface should be non-absorbent. Paper, unless varnished, should therefore be avoided. The best covering for these places is glazed tiling, or painted cement. Not uncommonly, a new paper is pasted over an old one; and this may be repeated several times. Under these circumstances dangerous dirt accumulates. Before new papering is put on, the walls should be cleared of all vestiges of the old, thoroughly washed down, and subsequently coated with size (that is, “clear coloured”). The sizing diminishes the absorptive power of the wall, and gives a good surface for applying the paper. Bed-room papers require to be more frequently changed than those of other rooms. Bed-rooms in regular use should be re-papered at least every two years. It is still better to use distemper for such rooms, as this can be washed off in a few hours with comparatively little expense, and can be made of any tint desired. Rooms in the basement should not be papered, as the walls require frequent washing down and cleaning. Here also a washable distemper colour can be used. Various kinds of sanitary paper are now sold which are washable, and relatively non-absorbent. Some of them require varnishing; others do not. Such papers are certainly cleaner than ordinary paper; but it would not be safe to trust to their non-absorptive character. Lincrusta Walton is non-absorbent, and can be scrubbed with soap and water; but it is expensive. Other cheaper materials possessing the same properties can now be bought.