It is equally difficult to speak positively and generally in reference to tea and coffee. It is safe to say, however, that many people drink these tempting beverages to excess, with harm resulting to themselves from it. Tea and coffee alike act as exciters of the nerve centers, accelerating and strengthening the heart’s action and respiration, causing wakefulness, and increasing the secretion of the kidneys and skin. Tea and coffee are far superior to alcohol in enabling man to resist the depressing influence of fatigue and exposure to cold, and are admirably adapted to the needs of soldiers on the march or men on outdoor night duty. Cocoa, chocolate and their preparations contain some active elements similar to those of tea and coffee, but the proportion of nutritive material is so much greater that they are to be looked on rather as food than drink. The considerable use of ice and iced drinks is to be avoided. Small quantities are of service in relieving thirst and vomiting, and in cooling the body when exposed to great heat. But since ice causes the mucous membrane of the stomach to become temporarily pale and bloodless, it checks or altogether suspends the flow of the gastric juice. Thus iced drinks at meals interfere seriously with digestion. Observe also that there is no truth in the popular notion that frozen water or ice is always pure. Water is not purified by freezing, and may be even more polluted than it was before. CLOTHING AND ITS RELATION TO HEALTH Having considered thus briefly the matter of food and its relation to health, the question of clothing and personal hygiene now rises for attention. Besides serving for covering and adornment and guarding the body from injury, the use of clothing is to help in preserving the proper animal heat in spite of external changes. In health the normal temperature of the body, ninety-eight to ninety-nine degrees Fahrenheit, is invariable. In order that this temperature shall be maintained with the least strain on the vitality, the clothing should be such that heat is not readily conducted to or from the body. Cotton and linen keep off the direct rays of the sun and favor the loss of heat from the body, but being bad absorbers of moisture they are apt to interfere with evaporation from the skin, and cause dangerous chills. Linen and cotton are good conductors of heat, especially the former, and do not readily absorb moisture. Silk and wool are bad conductors. Wool has also a remarkable power of so completely absorbing moisture that it feels dry when cotton or linen would be wet and cold. Its value as a non-conductor, retaining internal heat and excluding external heat, is shown by the fact that we wrap ice in blankets to keep it from melting, and cover teapots with woolen “cosies” to keep them from getting cold. These qualities together render it the most perfect material for clothing under all conceivable circumstances.