The importance of water in the human economy is manifest when we realise that quite 70 per cent. of the weight of the body is made up of water. It is to be met with not only in the actual tissue substance and as the chief ingredient in all the fluids of the body, but also in transit through the external and internal linings of the body. Without such watery transudation not only would the skin be extremely uncomfortable and the mucous and other lining membranes become painfully evident because of increased friction, but the body itself would suffer serious damage, because its temperature is regulated by this means.

Roughly speaking, about 4 1/2 pints of water are excreted from the body daily, and of this quantity about one half escapes by the kidneys, containing in solution urea, uric acid, and other waste matters from the breaking down of proteins; a little more than a quarter is excreted by the skin as sweat and sebaceous matter, containing some of the fats; a little less than a quarter by the lungs in the shape of watery vapour holding in solution waste matters from the breakdown of the carbohydrates and fats; and the residue (about 2 per cent.) escapes by the bowels. In a vegetarian, however, as much as 10 per cent. may be excreted by the bowels, creating a much more abundant and softer stool than in a mixed feeder.

It is important to note that more water is excreted than is ingested, because about 10 or 12 ounces are actually manufactured from the tissue itself during the process of combustion. It is, however, manifest that the balance must be supplied in the food and fluids consumed, and about half of the whole weight of solid food consists of water. This would leave a little more than two pints to be supplied in an actual fluid form, and it is probably judicious to drink the equivalent of six tumblerfuls of fluid each day. A considerable quantity is consumed as tea and coffee or similar beverages, but the more one can take as pure water the better, because one of the chief functions it subserves is to carry off in solution waste products from the body, and pure water is the best solvent known to chemists. Fat people and those who are out of condition are able to accommodate as much as five pounds of useless water in the interstices of their tissues, and one of the objects of training is to rid the body safely of this excess of fluid. Where a large proportion of protein is consumed the tissues are relatively free from water, whereas the body tends to become richer in water when the fats and carbohydrates are in excess in the diet.

Where the digestion is not impaired, it is an advantage to partake of water or other bland fluid at meal-times, as a better distribution of nutrient material is thereby obtained. Many people who live in a city, however, find that they are apt to suffer from indigestion if fluid is abundantly supplied at meal-times, and this is doubtless due to the fact that the stomach has become atonic and cannot effectually expel the fluid. It should be noted that fluids are always expelled from the stomach before solids.

The best time to take fluid is first thing in the morning and last thing at night, and most people find that a tumblerful of cold water in the morning immediately on rising and the same quantity of hot water at night just before retiring are valuable adjuncts to their diet, enabling them to obtain with comparative ease a daily evacuation of the bowels.