, in Physiology, a clear, insipid, and colourless fluid, coagulable into a transparent solid substance, called ice, when placed in a temperature of 32° of Fahrenheit's thermometer, or lower, but volatile and fluid in every degree of heat above that; and when pure, or freed from heterogeneous particles, is reckoned one of the four elements.

By some late experiments of Messrs. Lavoisier, Watt, Cavendish, Priestley, Kirwan, &c, it appears, that Water consists of dephlogisticated air, and inflammable air or phlogiston intimately united; or, as Mr. Watt conceives, of those two principles deprived of part of their latent heat. And in some instances it appears that air and Water are mutually convertible into each other. Thus, Mr. Cavendish (Philos. Trans. vol. 74, p. 128) recites several experiments, in which he changed common air into pure Water, by decomposing it in conjunction with inflammable air. Dr. Priestley likewise, having decomposed dephlogisticated and inflammable air, by firing them together by the electric explosion, found a manifest decomposition of Water, which, as nearly as he could judge, was equal in weight to that of the decomposed air. He also made a number of other curious experiments, which seemed to favour the idea of a conversion of Water into air, without absolutely proving it. The difficulty which M. De Lue and others have found in expelling all air from Water, is best accounted for on the supposition of the generation of air from Water; and admitting that the conversion of Water into air is effected by the intimate union of what is called the principle of heat with the Water, it appears sufficiently analogous to other changes, or rather combinations, of substances. Is not, says Dr. Priestley, the acid of nitre, and also that of vitriol, a thing as unlike to air as Water is, their properties being as remarkably different? And yet it is demonstrable that the acid of nitre is convertible into the purest respirable air, and probably by the union of the same principle of heat. Philos. Trans. vol. 73, p. 414 &c.

Indeed there seems to be Water in all bodies, and particles of almost all kinds of matter in Water; so that it is hardly ever sufficiently pure to be considered as an element. Water, if it could be had alone, and pure, Boerhaave argnes, would have all the requisites of an element, and be as simple as fire; but there is no expedient hitherto discovered for procuring it so pure. Rain Water, which seems the purest of all those we know of, is replete with infinite exhalations of all kinds, which it imbibes from the air: so that if siltered and distilled a thousand times, there still remain fæces. Besides this, and the numberless impurities it acquires after it is raised, by mixing with all sorts of effluvia in the atmosphere, and by falling upon and running over the earth, houses, and other places. There is also fire contained in all Water; as appears from its fluidity, which is owing to fire alone. Nor can any kinds of siltering through sand, stone, &c, free it entirely from salts &c. Nor have all the experiments that have been invented by the philosophers, ever been able to derive Water perfectly pure. Hence Boerhaave says, that he is convinced nobody ever saw a drop of pure Water; | that the utmost of its purity known, only amounts to its being free from this or that sort of matter; and that it can never, for instance, be quite deprived of salt; since air will always accompany Water, and air always contains salt.

Water seems to be diffused everywhere, and to be present in all space wherever there is matter. There are hardly any bodies in nature but what will yield Water: it is even asserted that fire itself is not without it. A single grain of the fiery salt, which in a moment's time will penetrate through a man's hand, readily imbibes half its weight of Water, and melts even in the driest air imaginable. Among innumerable instances, hartshorn, kept 40 years, and turned as hard and dry as any metal, so that it will yield sparks of fire when struck against a flint, yet being put into a glass vessel, and distilled, will afford 1/8th part of its quantity of Water. Bones dead and dried 25 years, and thus become almost as hard as iron, yet by distillation have yielded half their weight of Water. And the hardest stones, ground and distilled, always discover a portion of it. But hitherto no experiment shews, that Water enters as a principle into the combination of metallic matters, or even into that of vitrescible stones.

From such considerations, philosophers have been led to hold the opinion, that all things were made of Water. Basil Valentine, Paracelsus, Van Helmont, and others have maintained, that Water is the elemental matter or stamen of all things, and suffices alone for the production of all the visible creation. Thus too Newton: “All birds, beasts, and fishes, insects, trees, and vegetables, with their several parts, do grow out of Water, and watery tinctures, and salts; and by putrefaction they all return again to watery substances.” And the same doctrine is held, and confirmed by experiments, by Van Helmont, Boyle, and others.

But Dr. Woodward endeavours to shew that the whole is a mistake.—Water containing extraneous corpuscles, some of which, according to him, are the proper matter of nutrition; the Water being still found to afford so much the less nourishment, the more it is purified by distillation. So that Water, as such, does not seem to be the proper nutriment of vegetables; but only the vehicle which contains the nutritious particles, and carries them along with it, through all the parts of the plant.

Helmont however carries his system still farther, and imagines that all bodies may be reconverted into Water. His alkahest, he affirms, adequately resolves plants, animals, and minerals, into one liquor, or more, according to their several internal differences of parts; and the alkahest, being abstracted again from these liquors, in the same weight, and with the same virtues, as when it dissolved them, the liquors may, by frequent cohobations from chalk, or some other proper matter, be totally deprived of their seminal endowments, and at last return to their first matter; which is insipid Water.

Spirit of wine, of all other spirits, seems freest from Water: yet Helmont affirms, it may be so united with Water, as to become Water itself. He adds, that it is material Water, only under a sulphureous disguise. And the same thing he observes of all salts, and of oils, which may be almost wholly changed into Water.

No standard for the Weight and Purity of Water.— Water scarce ever continues two moments exactly of the same weight; by reason of the air and fire contained in it. The expansion of Water in boiling shews what effect the different degrees of fire have on the gravity of Water. This makes it difficult to fix the specific gravity of Water, in order to settle its degree of purity. However, the purest Water we can obtain, according to the experiments of M. Hawskbee, is 850 times heavier than air: or according to the experiments of Mr. Cavendish, the thermometer being at 50° and the barometer at 29 3/4, about 800 times as heavy as air: and according to the experiments of Sir Geo. Shuckburgh, when the barometer is at 29.27 and the thermometer at 53°, Water is 836 times heavier than air; whence also may be deduced this general proportion, which may be accounted a standard, viz, that, when the barometer is at 30° and the thermometer at 55°, then Water is 820 times heavier than air; also that in such a state the cubic foot of Water weighs 1000 ounces avoirdupois, and that of air 1.222, or 1 2/9 nearly, also that of mercury 13600 ounces; and for other states of the thermometer and barometer, the allowance is after this rate, viz, that the column of mercury in the barometer varies its length by the 10 thousandth part of itself for a change of each single degree of temperature, and Water changes by 3/20000 part of its height or magnitude by each degree of the same. However, we have not any very exact standard in air; for Water being so much heavier than air, the more Water there is contained in the air, the heavier of course must the air be; as indeed a considerable part of the weight of the atmosphere seems to arise from the Water that is in it.

Properties and Effects of Water.—Water is a very volatile body. It is entirely reduced into vapours and dissipated, when exposed to the fire and unconfined.

Water heated in an open vessel, acquires no more than a certain determinate degree of heat, whatever be the intensity of the fire to which it is exposed; which greatest degree of heat is when it boils violently.

It has been found that the degree of heat necessary to make Water boil, is variable, according to the purity of the Water and the weight of the atmosphere. The following table shews the degree of heat at which Water boils, at various heights of the barometer, being a medium between those resulting from the experiments of Sir Geo. Shuckburgh and M. De Luc:

Height of theHeat of Boiling
26 1/2206
27 1/2207.7
28 1/2209.4
29 1/2211.2
30 1/2212.8

Water is found the most penetrative of all bodies, after fire, and the most difficult to confine; passing through leather, bladders, &c, which will confine air; making its way gradually through woods; and is only retainable in glass and metals; nay it was found by experiment at Florence, that when shut up in a spherical vessel of gold, which was pressed with a great force, it made its way through the pores even of the gold itself.

Water, by this penetrative quality alone, may be inferred to enter the composition of all bodies, both vegetable, animal, fossil, and even mineral; with this particular circumstance, that it is easily, and with a gentle heat, separable again from bodies it had united with.

And yet the same Water, as little cohesive as it is, and as easily separated from most bodies, will cohere firmly with some others, and bind them together in the most solid masses; as in the tempering of earth, or ashes, clay, or powdered bones, &c, with Water, and then dried and burnt, when the masses become hard as stones, though without the Water they would be mere dust or powder. Indeed it appears wonderful that Water, which is otherwise an almost universal dissolvent, should nevertheless be a great coagulator.

Some have imagined that Water is incompressible, and therefore nonelastic; founding their opinion on the celebrated Florentine experiment above mentioned, with the globe of gold; when the Water being, as they say, incapable of condensation, rather than yield, transuded through the pores of the metal, so that the ball was found wet all over the outside; till at length making a clest in the gold, it spun out with great vehemence. But the truth of the conclusions drawn from this Florentine experiment has been very justly questioned; Mr. Canton having proved by accurate experiments, that Water is actually compressed even by the weight of the atmosphere. See Compression.

Besides, the diminution of size which Water suffers when it passes to a less degree of heat, sufficiently shews that the particles of this fluid are, like those of all other known substances, capable of approaching nearer together.

Ditch Water, is often used as an object for the microscope, and seldom fails to afford a great variety of animalcules; often appearing of a greenish, reddish, or yellowish colour, from the great multitudes of them. And to the same cause is to be ascribed the green skim on the surface of such Water. Dunghill Water is also full of an immense crowd of animalcules.

Fresh Water, is said of that which is insipid, or without salt, and inodorous; being the natural and pure state of the element.

Hard Water, or Crude Water, is that in which soap does not dissolve completely or uniformly, but is curdled. The dissolving power of hard Water is less than that of soft; and hence its unfitness for washing, bleaching, dyeing, boiling kitchen vegetables, &c.

The hardness of Water may arise either from salts, or from gas. That which arises from salts, may be discovered and remedied by adding some drops of a solution of fixed alkali; but the latter by boiling, or exposure to the open air.

Spring Waters are often hard; but river Water soft. Hard Waters are remarkably indisposed to corrupt; they even preserve putrescible substances for a considerable length of time: hence they seem to be best fitted for keeping at sea, especially as they are so easily softened by a little alkaline salt.

Putrid Water, is that which has acquired an offensive smell and taste by the putrescence of animal or vegetable substances contained in it. This kind of Water is in the highest degree pernicious to the human frame, and capable of bringing on mortal diseases even by its smell. Quicklime put into water is useful to preserve it longer sweet; or even exposure to the air in broad shallow vessels. And putrid Water may be in a great measure sweetened, by passing a current of fresh air through it, from bottom to top.

Rain Water may be considered as the purest distilled Water, but impregnated during its passage through the air with a considerable quantity of phlogistic and putrescent matter; whence it is superior to any other in fertilizing the earth. Hence also it is inferior for domestic purposes to spring or river Water, even if it could be readily procured: but such as is gotten from spouts placed below the roofs of houses, the common way of procuring it in this country, is evidently very impure, and becomes putrid in a short time.

River or Running Water, is next in purity to snow or distilled water; and for domestic purposes superior to both, in having less putrescent matter, and more fixed air. That however is much the purest that runs over a clean rocky or stony bottom.

River Waters generally putrefy sooner than those of springs. During the putrefaction, they throw off a part of their heterogeneous matter, and at length become sweet again, and purer than at first; after which they commonly preserve a long time: this is remarkably the case with the Thames Water, taken up about London; which is commonly used by seamen, in their voyages.

Salt Water, such as has much salt in it, so as to be sensible to the taste.

Sea Water, or Water of the sea, is an assemblage of bodies, in which Water can scarce be said to have the principal part: it is an universal colluvies of all the bodies in nature, sustained and kept swimming in Water as a vehicle: being a solution of common salt, sal catharticus amarus, a selenitic substance, and a compound of muriatic acid with magnesia, mixed together in various proportions. It may be freshened by simple distillation without any addition, and thus it has sometimes been useful in long voyages at sea. Sea Water by itself has a purgative quality, owing to the salts it contains; and has been greatly recommended in scrophulous disorders.

Sea Water is about 3 parts in 100 heavier than common Water; and its temperature at great depths is from 34 to 40 degrees; but near the surface it follows more nearly the temperature of the air.

Snow Water, is the purest of all the common Waters, when the snow has been collected pure. Kept in a warm place, in clean glass vessels, not closely stopped, but covered from dust, &c, snow water becomes in time putrid; though in well-stopped bottles it remains unaltered for several years. But distilled Water suffers no alteration in either circumstance.

Spring Water is commonly impregnated with a | small portion of imperfect neutral salt, extracted from the different strata through which it percolates. Some contain a vast quantity of stony matter, which they deposit as they run along, and thus form masses of stone; sometimes incrustating various animal and vegetable matters, which they are therefore said to petrify. Spring-Water is much used for domestic purposes, and on account of its coolness is an agreeable drink; but on account of its being usually somewhat hard, is inferior to that which has run for a considerable way in a channel.

Spring-water arises from the rain, and from the mists and moisture in the atmosphere. These falling upon hills and other parts of the earth, soak into the ground, and pass along till they find a vent out again, in the form of a spring.

Water-Bellows, in Mechanics, are bellows, for blowing air into furnaces, that are worked by the force of water.

Water-Clock. See Clepsydra.

Water-Engine, an engine for extinguishing fires; or any engine to raise water; or any engine moved by the force of Water. See Engine, and Steam-Engine.

Water-Gage, an instrument for measuring the depth or quantity of any water. See Gage.

Water-Level, is the true level which the surface of still Water takes, and is the truest of any.

Water-Logged, in Sea-Language, denotes the state of a ship when, by receiving a great quantity of Water into her hold, by leaking, &c, she has become heavy and inactive upon the sea, so as to yield without resistance to the effort of every wave rushing over her deck.

Water-Machine. See Machine.

Water-Measure. Salt, sea-coal, &c, while on board vessels in the pool, or river, are measured with the corn-bushel heaped up; or else 5 striked pecks are allowed to the bushel. This is called Water-measure; and it exceeds Winchester-measure by about 3 gallons in the bushel.

Water-Microscope. See Microscope.

Water-Mill. See Mill.

Motion of Water, in Hydraulics. The theory of the motion of running Water is one of the principal objects of hydraulics, and to which many eminent mathematicians have paid their attention. But it were to be wished that their theories were more consistent with each other, and with experience. The inquisitive reader may consult Newton's Principia, lib. 2, pr. 36, with the comment. Dan. Bernoulli's Hydrodynamica. J. Bernoulli, Hydraulica, Oper. tom. 4, pa. 389. Dr. Jurin, in the Philos. Trans. num. 452, or Abridg. vol. 8, pa. 282. Gravesande, Physic. Elem. Mathem. lib. 3, par. 2. Maclaurin's Flux. art. 537. Poleni de Castellis, Ximenes, D'Alembert, Bossu, Buat, and many others.

But notwithstanding the labours of all these eminent authors, this intricate subject still remains in a great measure obscure and uncertain. Even the simple case of the motion of running water, when it issues from a hole in the bottom of a vessel, has never yet been determined, so as to give universal satisfaction to the learned. On this head, it is now pretty generally allowed, that the velocity of the issuing stream, is equal to that which a heavy body acquires by falling through the height of the fluid above the hole, as may be demonstrated by theory: but in practice, the quantity of the effluent Water is much less than what is given by this theory; owing to the obstruction to the motion in the hole, partly from the sides of it, and partly from the different directions of the parts of the Water in entering it, which thence obstruct each other's motion. And this obstruction, and the diminution in the quantity of Water run out, is still the more in proportion as the hole is the smaller; in such sort, that when the hole is very small, the quantity is diminished in the ratio of √2 to 1 very nearly, which is the ratio of the greatest diminution; and for larger holes, the diminution is always less and less. This fact is ascertained, or admitted by Newton, and all the other philosophers abovementioned, with some small variations.

That the velocity of the Water in the hole, or at least some part of it, as that for example in the middle of the stream, is equal to that abovementioned, is even evinced by experiment, by directing the stream either sideways, or upwards: for in the former case, it is found to range upon an horizontal plane, a distance that just answers to that velocity, by the nature of projectiles; and in the latter case, the jet rises nearly to the height of the Water in the vessel; which it could not do, if its velocity were not equal to that acquired by the free descent of a body through that height. Hence it is evident then, that the particles of the Water, which are in the hole at the same moment of time, do not all burst out with the same velocity; and, in fact, the velocity is found to decrease all the way from the middle of the hole, where it is greatest, towards the side or edge, where it is the least.

At a small distance from the hole, the diameter of the vein of Water is much less than that of the hole. Thus, if the diameter of the hole be 1, the diameter of the vein of Water just without it, will be 21/25, or 0.84, according to Newton's measure, who first observed this phenomenon; and according to Poleni's measure 0.78 nearly.

By the experiments of Buat (Principes d'Hydraulique), the quantity by theory is to that by experiment, for a small hole made in the thin side of a reservoir, as 8 to 5. When a short pipe is added to the hole outwards, of the length of two or three times its diameter, that ratio is as 16 to 13. And when the short pipe is all within side the vessel, as in the margin, the same ratio becomes that of 3 to 2. Poleni also found that the quantity of Water flowing through a pipe or tube, was much greater than that through a hole of the same diameter in the thin side or bottom of the vessel, the height of the head of Water above each being the same. See also many other curious circumstances in Buat's Principes above mentioned.

Some authors give this rule for finding the height due to the velocity in a flat orifice, or a medium among all the parts of it, such that this medium velocity being drawn into the area of the hole, shall give the quantity per second that runs through: viz, let A denote the | area of the surface of the Water in the vessel, a the area of the orifice by which the Water issues, and H the height of the Water above the orifice; then, as 2A - a : A :: H : b, the height due to the medium velocity, or the height from which a body must freely descend, by the force of gravity, to acquire that mean velocity.

Authors are not yet agreed as to the force with which a vein of Water, spouting from a round hole in the side of a vessel, presses upon a plane directly opposed to the motion of the vein. Most authors agree, that the pressure of this vein, flowing uniformly, ought to be equal to the weight of a cylinder of Water, whose base is equal to the hole through which the Water flows, and its height equal to the height of the Water in the vessel above the hole. The experiments made by Mariotte, and others, seem to countenance this opinion. But Dan. Bernoulli rejects it, and estimates this pressure by the weight of a column of the fluid, whose diameter is equal to the contracted vein (according to Newton's observation abovementioned), and the height of which is equal to double the altitude due to the real velocity of the spouting Water; and this pressure is also equal to the force of repulsion, arising from the reaction of the spouting Water upon the vessel. The ingenious author remarks that he speaks only of single veins of Water, the whole of which are received by the planes upon which they press; for as to the pressures exerted by fluids surrounding the bodies they press upon, as the wind, or a river, the case is different, though confounded with the former by writers on this subject. Hydrodynamica, pa. 289.

Another rule however had been adopted by the Academicians of Paris, who made a number of experiments to confirm or establish it. Hist. Acad. Paris, ann. 1679, sect. 3, cap. 5.

D. Bernoulli, on the other hand, thinks his own theory sufficiently established by the experiments he relates; for the particulars of which see the Acta Petropolitana, vol. 8, pa. 122.

This ingenious author is of opinion that his theory of the quantity of the force of repulsion, exerted by a vein of spouting Water, might be usefully applied to move ships by pumping; and he thinks the motion produced by this repulsive force would fall little, if at all, short of that produced by rowing. He has given his reasons and computations at length in his Hydrodynamica, pa. 293 &c.

This science of the pressures exerted by Water or other fluids in motion, is what Bernoulli calls Hydraulico-statica. This science differs from hydrostatics, which considers only the pressure of Water and other fluids at rest; whereas hydraulico-statics considers the pressure of Water in motion. Thus the pressure exerted by Water moving through pipes, upon the sides of those pipes, is an hydraulico-statical consideration, and has been erroneously determined by many, who have given no other rules in these cases, but such as are applicable only to the pressure of fluids at rest. See Hydrodynam. pa. 256 &c.

Water-Poise. See Hydrometer, and AREOMETER.

Dr. Hook contrived a Water-poise, which may be of good service in examining the purity &c of Water. It consists of a round glass ball, like a bolt head, about 3 inches diameter, with a narrow stem or neck, the 24th of an inch in diameter; which being poised with red lead, so as to make it but little heavier than pure sweet Water, and thus fitted to one end of a fine balance, with a counterpoise at the other end; upon the least addition of even the 2000th part of salt to a quantity of Water, half an inch of the neck will emerge above the water. Philos. Trans. num. 197.

Raising of Water, in Hydraulics. The great use of raising Water by engines for the various purposes of life, is well known. Machines have in all ages been contrived with this view; a detail of the best of which, with the theory of their construction, would be very curious and instructive. M. Belidor has executed this in part in his Architecture Hydraulique. Dr. Desaguliers has also given a description of several engines to raise Water, in his Course of Experimental Philosophy, vol. 2, and there are several other fmaller works of the same kind.

Engines for raising Water are either such as throw it up with a great velocity, as in jets; or such as raise it from one place to another by a gentle motion. For the general theory of these engines, see Bernoulli's Hydrodynamica.

Desaguliers has settled the maximum of engines for raising water, thus: a man with the best Water engine cannot raise above one hogshead of Water in a minute, 10 feet high, to hold it all day; but he can do almost twice as much for a minute or two.

Water-Spout. See Spout.

Water-Wheel, an engine for raising Water in great quantity out of a deep well, &c. See Persian- Wheel.

Water-Works. See Raising of Water.

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Entry taken from A Mathematical and Philosophical Dictionary, by Charles Hutton, 1796.

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