Natural water, the purest that can be obtained, cleared, if necessary, by filtration, and free from odour, taste, and visible impurity.

From Aqua is made:

Aqua Destillata. - H1O. Pure water, obtained by distillation.

Preparations.

Very numerous throughout the whole Pharmacopoeia.

Action And Uses. 1. Immediate Local Action And Uses

Externally, water acts chiefly as a means of applying heat or cold to the surface of the body, being readily obtained at any temperature that may be desired. To produce this effect, water may be applied in the form of baths of all kinds: Cold, cool, temperate, tepid, warm, hot, vapour, or variously medicated; also by sponging, douching, fomenting, etc. These subjects will be noticed in the third part of the work. Possessing these properties, water is used externally for purposes of cleanliness; for either raising or lowering the temperature of the body; relieving pain, insomnia, and delirium; removing spasms or convulsions; diminishing the circulation in deep parts by superficial "derivation," as in congestion of the brain, etc. Water is also used, in a purely local way, as a wash or dressing to wounds, and as the basis of warm fomentations in inflammations.

Internally, water is constantly being taken in the form of food and drink. It relieves thirst, improves digestion and in testinal action when drunk in moderation and at proper times, and in a purely physical way may reduce the local or general temperature of the body, for instance, as ice slowly sucked iu sore throat and febrile conditions.

2. Action On The Blood

"Water is quickly incorporated with the circulating plasma. Great excess has been known to dissolve part of the red corpuscles, but this is a purely pathological effect.

3. Specific Action And Uses

Water plays an essential part in tissue life and in the activity of all the organs. A copious supply of water increases nutrition up to a certain point, especially the deposit of fat, and is therefore extensively employed in hydro-therapeutics.

4. Remote Local Action And Uses

Water is excreted by the kidneys, skin, lungs, bowels - indeed, necessarily in every secretion. Increase of water in the urine is most readily induced when the skin is kept cool, and carries with it an excess of urea, phosphoric acid, and chloride of sodium. Water is thus a diuretic, and in one sense the most natural measure of the kind, being indicated when we desire simply to irrigate or flush the uriniferous tubules and urinary passages, and wash from them the products of disease, such as blood, leucocytes, cellular debris, and sediments. Some kinds of calculi may he dissolved by the steady consumption of distilled water, which carries away minute traces of the stone, whilst it prevents fresh accretion on the surface.

As a diaphoretic, water acts best when warm and combined with external heat. It is the basis of most familiar domestic measures for relieving feverishness by inducing perspiration, such as warm drinks of all kinds, and spirituous compounds.