In preparing a specimen you will need a covered corked vessel large enough to hold all the urine passed in twenty-four hours, and it must be thoroughly washed and scalded. The next step is to pass urine, suppose we say at eight o’clock in the morning, and throw it away. All of the urine which you pass after this time until eight o’clock the next morning must be saved in the vessel and kept in a cool place to prevent its decomposing. If you will put a teaspoonful of chloroform or boracic acid powder into the vessel it will tend to preserve the urine and will not injure the specimen. At the end of twenty-four hours the urine should be shaken to mix it thoroughly and about half a pint poured into a bottle that has been washed and scalded. Carefully cork and label this with the date, your name and address and the total amount of urine passed in the twenty-four hours. The vessel for collecting the urine and whatever you use as a measure should be reserved for these purposes only. If you have no tin or glass measure, a regular-size quart tomato can will prove entirely satisfactory. If you find, when measuring your urine, that you pass less than a quart and a half in twenty-four hours, you may know without being told that this is not enough and that you should drink more water. =The Skin.= People are likely to think of the skin as being simply a covering for the body, whereas, in reality, it is a very complicated and active organ which helps to regulate the body temperature and constantly throws off impurities, just as the kidneys do. This latter function is performed by the sweat glands which open upon the surface of the skin as the “pores,” and we are told that in all there are some twenty-eight miles of these tiny tube-like structures in the skin. These glands should be, and usually are, constantly active; they pour upon the surface of the body an oily substance which keeps the skin soft; they also excrete something more than a pint of water daily, which contains impurities that are harmful if retained in the body. We are not aware of this constant excretion of fluids, which is termed “insensible perspiration,” but it continues even in cold weather and must not be stopped if health is to be preserved. If the oil, dust, particles of dead skin and the waste material left by dried perspiration are allowed to remain upon the surface of the body they will clog the pores, or gland openings, and thus interfere with their action. The removal of this material, then, is necessary to maintain health, and is done automatically in part for the fluid evaporates and much of the solid matter is rubbed off on the clothing. The most important aids to the skin’s activity are the drinking of plenty of water, deep breathing, exercise and warm baths. Regular and thorough bathing serves the double purpose of removing waste matter already on the surface, and of stimulating the glands to increased activity in giving off still more.