Linen is the most absorbent material for underwear. It soaks up moisture very rapidly, and dries with equal rapidity. Hence linen is always preferred for towels and bandages. Those who use it for underwear will not require to change the clothes after exercise, as they would if wool were worn next the skin. The ordinary woven linen is clean but cold: Kneipp linen is so constructed as to be clean and warm. This material retains air in its meshes, and a layer of dry air next the body is the best method of preserving an even temperature, and thus avoiding colds and chills, which are so prevalent in a climate such as ours. Wool is entirely unsuited for wearing next the skin. It does not absorb the perspiration rapidly nor radiate it freely, and after several washings it becomes felted, and in that condition is absolutely injurious to health. It is the material par excellence for outer clothing, but all inner garments coming in contact with the body should be composed of pure linen. (_See_ Skin, Care of). Uric Acid.--This acid is found in persons of a gouty tendency, such tendencies being a great deal more common than is imagined. It is really a waste product formed by the activity of the body cells, and should properly be mainly transformed into urea and so excreted. If it is not so transformed it accumulates in the blood and deposits in stony formations in different parts of the body, as in the joints, kidneys and bladder, causing very serious disease. Pure air and plenty of exercise will assist its transformation. It is also taken into the body in various foods, particularly meat and tea, which are very rich in it or kindred chemical substances, therefore, anyone having such a tendency should avoid these. The consumption of sugar should also be limited. Avoid alcohol and use plenty of green vegetables and fruits. The tendency to a "uric acid" constitution is hereditary, and is prevalent among families who live high. Such should be continually on the watch lest their diet should precipitate an attack. Water should be freely drunk, and plenty of bathing with subsequent rubbing of the muscles or massage is advisable. Drugs are to be avoided as they often result in painful heart affection, and besides do not strike at the real root of the disease. Soda or lithia water may be taken either with or without milk. Brine baths may be taken when practicable. Urinary Troubles.--A healthy man usually evacuates about 30-40 ozs. of urine daily, the excretion being greater in the winter than in the summer, owing to the checked perspiration. The urine should be of a pale straw colour and transparent. Where any irregularity in the urine, either in quantity or quality, is suspected, it is wise to use soft boiled or distilled water only, for drinking, and to take frequent sips of it throughout the day, and especially early in the morning. Either pure hot water, hot water and lemon juice, or whey, will help the action of the kidneys when this is sluggish.