Warm baths are best taken at night, just before going to bed, though the danger of catching cold after them on account of their "opening up the pores of the skin," has been very greatly exaggerated. They have, however, a relaxing effect upon the skin, and take out an undue amount of the natural oil which nature provides for its oiling and softening, so that, except for special reasons, it is best not to take them oftener than once, or twice, a week. Soaps and Scrubbing Brushes. As part of the perspiration deposited upon our skins is in the form of a delicate oil, and as this oil may become mixed with dirt, or dust, and form a mixture not readily soluble in water, it is at times advisable to add to the water something that will dissolve oil. The commonest thing used for this purpose is soap, which is a combination of an _alkali_--most commonly _soda_, though occasionally _potash_ (lye) is used in the soft soaps--with a fat or an oil. The combination of the two, which we call soap, has been invented for two reasons; one, that it makes a convenient, solid form in which the alkali, needed to dissolve the body oil, can be used in such strength as not to burn or injure the skin; the other, that the fat in the soap will, to some extent, take the place of the natural oil, or fat, which it washes off. Necessary as soap is, it should be used very moderately. You should never lather and scrub your skin as if it were a kitchen floor, for the reason that, with the dirt, the alkali also washes and dissolves out a considerable amount of the natural oil of the skin, and leaves it harsh and dry. On this account, it is best not to use soap upon the covered portions of the body, and in the full bath, oftener than once or twice a week; and upon the face, oftener than once or twice a day. But the hands may be washed with soap more frequently. It is also best to avoid the too frequent use of hot water, even upon the hands and face, for the same reason; it takes out too much of the natural oil of the skin, along with the dirt. Unless the dirt be of some infectious, or offensive, character, it is often best to content yourself with washing off just the "big dirt," and wait for the bubbling up of the perspiration through your skin to bring the deeper dirt up to the surface, and wash that off later, in the course of two or three hours. Soaps to be Avoided. Soaps that lather too quickly and easily should always be avoided, for this shows that they contain an excessive amount of soda or other alkali. It is also best to avoid, or at least be very wary of, any soaps which are dark-colored or heavily perfumed, as these disguises may indicate the presence of decaying, offensive fats, and even of grease extracted from garbage. This is what strong perfumes in soaps are chiefly used for. Beware of all such, and especially of tar soaps, for the black color and the strong odor of tar can cover up any amount of bad quality.