oxidation of the lead. These * Containing 4.05 grains of solid matter to the gallon, or about one 18,000 part. 147 pipes have been highly recommended by our first chemists, and other men of sci- ence, as furnishing an effectual safeguard against the corroding effects of pure water This highly ingenious process, strengthens the pipe, without diminishing its elas- ticity, and although some small portions of the lead should escape being coated, yet the proximity of the tin, will, from galvanic action, probably prevent oxidization of the lead. As these pipes are furnished at about eight cents per pound, the usual price of ordinary lead-pipe, there can be no doubt that they will be generally adopt- ed by our citizens, — as they have been, already, by the Corporation, in the convey- ance of the Croton water, into the public buildings. Use of Water as Aliment. Water is the beverage provided by nature for all ani- mated beings. It is a vital stimulus, or one of the external conditions essential for the manifestations of life. Consequently, without it, life, at least in the higher order of animals, could not be maintained. Considered in a dietetical point of view, water serves three important purposes in the animal economy ; namely, it repairs the loss of the aqueous part of the blood, caused by the action of the secreting and exhaling organs ; secondly, it is a solvent of various alimentary substances, and therefore assists the stomach in the act of di- gestion, though, if taken in very large quantities, it may have an opposite effect, by diluting the gastric juice ; thirdly, it is a nutritive agent, that is, it assists in the formation of the solid parts of the body. As a diluent, water is indispensable to the preservation of health. The body being composed of solids and fluids, there must be maintained a certain relative proportion of these, to constitute that state of system called health. In a full grown adult, the solid matter of the body, by which we mean all that substantial part of the frame which is not in constant motion in the vessels, amounts to only about one fifth of the weight of the body — Chaussier says, one ninth of the total weight, the difference, perhaps, being- owing to the fact that there is a quantity of fluid combined with the solids in so intimate a manner, as almost to constitute a part of their substance. The diminution of the fluid part of the body, is the cause of an uneasy sensation, indicating the necessity of repairing the waste of fluids, which we familiarly call thirst. This is a sensation connected with some natural state of the corporeal funo tions, and altogether independent of the occasional excitement of foreign bodies, although it may be induced by these. There is a demand for a certain supply of liquid which is the result of repletion of the stomach, and the cause of our drinking at our ordinary meals, but this is different from true or spontaneous thirst. True thirst occurs, when we have been some time without taking drink, (unless the food has consisted mainly of fruits and other succulent vegetables ; under which circum- stances, a person may go for months without any desire for drink); when the system 148 has been greatly excited, whether by corporeal or mental causes ; when acid sub- stances, particularly saline bodies, have been taken into the stomach ; and, in short, in every condition of the system, which favors the inordinate excretion of fluids. The immediate cause of thirst appears to be a dry state of the mouth and fauces ; owing to the mucus which covers these parts becoming thick and viscid, though physiologists are not agreed on this point. This may arise from the absorption of the fluid parts of the saliva ; for it appears to be necessary for the due perform- ance of the functions of the palate and the tongue, that the mucus should possess a certain degree of liquidity. The sensation of thirst is generally indicative of the necessity of a supply of fluid to the system generally ; for although thirst may be momentarily assuaged by wetting the mouth, or holding a thin fluid in it — yet it can only be effectually relieved by conveying into the stomach a quantity of fluid sufficient to supply the deficiency. This supply is termed dilution, from the fact that the fluid is absorbed and carried into the blood, which it renders thin, and the fluids themselves are called diluents. Thirst, however, does not always indicate a deficiency of fluids in the circu- lating mass, and the tongue and fauces are occasionally dry and harsh whilst the sensation of thirst is absent. Some individuals