A body weighing one hundred and twenty pounds, if dried till free from all its liquids, would weigh but twenty pounds—while three-fourths, by weight, of the human body is water. If we were to make a box 16 inches square and the same deep, (a cube of 16 inches,) with walls one inch thick, and fill it with water, the ratio of water to wood would very nearly represent the relative proportions of solid and liquid constituents of the human body, both by weight and volume. Having taking a hasty glance at the magnitude of the demand of organized nature form water, we will pursue it no farther in a general way, but confine ourselves to _man’s_ particular need and the character and sources of supply. To obtain the quantity, which he requires to meet the demands of his system, a man consumes every year, about three-fourths of a ton, or fifteen hundred pounds of water. Some of this supply comes, of course, from waste and vegetables, which are, on an average, three-fourths water, and from bread, which will average 45 per cent. A certain quantity is also generated in the combustion of food, but the greater proportion is taken in drink. It will suffice to mention one or two of the uses of this water, which plays such an important part in our system. It gives a medium of circulation—of transportation—to solid, inert substances. As the great oceans and mighty rivers of earth bear upon their bosoms noble ships, freighted with the wealth of nations, so in the blood the precious corpuscles are coursing, borne on in their life-giving, life-sustaining mission, by the water in which they float. So in the milk and other animal creation, water bears safely a freight of valuable, solid particles, or carries off useless solids in solution. It gives pliancy to muscle and flesh, and serves many another purpose in the economy of the human system. It can be seen from the outlines we have just given, without the need of a further demonstration, that the _quality_ of drinking-water is of the utmost importance. It is strange, but true, that man needs to be protected, even by force, against himself, and this is well exemplified in the matter of drinking-water. One of the first and last labors of every State or city Board of Health is to prevent men from poisoning their drinking-water or allowing others to do it for them, and to keep them from using it, when it is thus poisoned. Those who live in the country are often prone to thank God that they live beyond the reach of sewer gases and other poisonous contaminations of city wells; but, before being too confident, let us ask ourselves the question, “are the people of our villages, or on our farms and plantations, entirely free from typhoid fever, diphtheria and other diseases, whose origin is so _often_ traced to impure drinking-water.” But what is pure water? It may surprise some of our readers when we state that _absolutely pure_ water, used constantly, is unhealthy!