It has been already noticed, that although no natural water is found in a state of absolute purity, yet that in general the quantity of foreign matters is not sufficient to give any very sensible taste or odour. In some instances, however, the foreign matter is so considerable, and of such a nature, as to prevent the water from forming a part of the nourishment of animals; in which case it is denominated a Mineral Water, and can be useful to mankind only in a medicinal point of view.

Mineral waters may be arranged into the five following classes : - 1.. Acidulous Waters; 2. Alkaline Waters; 3. Chalybeate Waters; 4 Sulphureous Waters; 5. Saline Waters. I shall first give a sketch of the physical characters and medicinal properties of each of these classes; and then describe the method of determining the ingredients, and their proportions, contained in any mineral water.

1. Acidulous Waters owe their properties chiefly to carbonic acid. They sparkle when drawn from the spring, or when poured into a glass? have an acidulous taste, and become vapid when exposed to the air. Besides free carbonic acid, on the presence of which these qualities depend, acidulous waters contain generally also carbonates of soda, bicarbonates of lime, of magnesia, and of iron.

They may be divided into thermal, or warm acidulous waters, and cold acidulous waters; the temperature of the former, however, does not exceed 72°, while that of the latter is generally about 55°.

Of this kind are the springs of Cleves in Germany; Granshaw in Ireland; Languac, Upper Loire; Orston and Thorston, Nottinghamshire; Passi, near Paris; Stonefield, Lincolnshire; Tonstein in Germany; Wisbaden in Nassau; and Bandola in Italy; but the most celebrated springs of this class are Pyrmont, Seltzer, Spa, and Carlsbad. They are tonic and diuretic; and in large doses produce a sensible degree of exhilaration. They all afford a grateful and moderate stimulus to the stomach; but the Pyrmont and Spa, containing carbonate of iron, are especially useful in all cases of impaired digestion; while those which contain alkaline carbonates, as the Carlsbad and Seltzer, are more particularly employed as palliatives in calculous affections.

2. Alkaline Waters owe their properties to a free alkali or one very slightly carbonated. They display an alkaline reaction. Alkaline springs are not very numerous.

3. Chalybeate Waters owe their properties to iron, in combination generally with carbonic acid; and as this is usually in excess, they are often acidulous as well as chalybeate. The metal is found also in the form of a sulphate, but the instances of this are very rare.

Chalybeate waters have a styptic or inky taste; they are, when newly drawn, transparent, and strike a black with tincture of nut-galls; but an ochry sediment, a hydrated peroxide of iron, soon falls, and the water loses its taste. If the iron be in the state of sulphate and hydrochlorate, however, no sediment falls; and the black colour is produced by the above test, even after the water has been boiled and filtered. Chalybeate springs are very numerous. On the Continent are those of Abcourt, St, Germain; Aumale and Forges, near Rouen; Bologne;

Buzot, in Spain (a warm spring); Caroline baths, Bohemia; Daswild, Baden, Germany; Driburgin, Westphalia; Naptha, in Russia; Nisdeniee, in Germany; Swalbach, in Nassau, Ponges, Hassenfratz; Perekop, Russia; Sarepta, Russia; Scolliensis, Switzerland; Suchakla, Hungary; and Vechy, near Moulius. There are many chalybeates in Great Britain; as, for instance, those of Arbroath and Peterhead in Scotland; Ashton, in Wiltshire; Balemore, Worcestershire; Ballycastle, Antrim; Ballynahinch, Down; Ballyspellan, Kilkenny; Bandon, Cork; Bromley, Kent; Brownstown, Kilkenny; Castlecomer, Kilkenny; Castleconnel, Limerick; Castlemain, Kerry; Coalcullen, Kilkenny; Corville, Tipperary; Coventry; Crosstown, Waterford; Doneraile, Cork; Dunnard, Dublin; Galway; Garry-hill, Carlow; Haigh, Lancashire; Hamp-stead; Hartfell, Scotland; Islington; Kilcoran, Clare; Kilagee, Down; Kirby, Westmoreland; Lancaster; Llandridad, Wales; Luz, Essex; Listerlin, Kilkenny; Milltown, Mallay, Clare; Newton Stewart, Tyrone; Oakfield, Cavan; Phoenix Park, Dublin; Scool, Clare; Shadwell, near London; Somersham, Huntingdonshire; and many others : but the most celebrated are Tunbridge, Brighton, and Peterhead; the Cheltenham spring also contains carbonate of iron; but on account of the large proportion of saline matter, and its strong purgative properties, it is not ranked in this class.

The Spa springs also belong to this class.

Chalybeate waters are powerful tonics, and are employed in dyspepsia, scrofulous affections, cancer, amehorrhoea, chlorosis, and the other diseases of debility for which the artificial preparations of iron are used. Much of the benefit derived from the use of chalybeate waters depends on the exlreme division of the metallic salts they contain, as well as the vehicle in which it is held in solution; while at the same time their operation is much modified by the carbonic acid by which the iron is suspended. When the water is a carbonated chalybeate, it should be drunk the moment it is drawn from the spring; but the same precaution is not necessary with a water containing sulphate of iron.

4. Sulphureous Waters derive their character chiefly from sulphuretted hydrogen gas; which in some of them is uncombined, while in others it is united with lime or an alkali. They are transparent when newly drawn from the spring, and have the foetid odour of rotten eggs, which is gradually lost by exposure to the air, and the water becomes turbid. When they are strongly impregnated with the gas, they redden infusion of litmus; and, even in a weak state, they blacken silver and lead. Besides containing sulphuretted hydrogen gas, they are not un-frequently, also, impregnated with carbonic acid. They generally contain chloride of magnesium or other saline matters, which modify their powers as a remedy.

The most important sulphureous springs in this island are those of Kilburn, Harrowgate, and Moffat; but the following are also of some note : Annaduff, Leitrim; Askeron in Yorkshire; Broughton in Yorkshire; Clonmel, Tipperary; Codsalwood, Staffordshire; Derrylister, Cavan; Drumasnane, Leitrim; Dudley, Worcestershire; Kedlistone, Derbyshire; Killashen, Fermanagh; Loansbury, Yorkshire; Maudley, Lancashire; Nottington, Dorsetshire; Ripon, Yorkshire; Shapmoor, Westmoreland; Wardrew, Northumberland; and Wirks-worth in Derbyshire. On the Continent, Aix-la-Chapelle; Barege; Baden; Baia, Italy; Dux, Bayonne; Ems, Germany; Montmorency, near Paris; Motte, near Grenoble; Viterbo in Italy; and St. Amands, near Valenciennes; which are resorted to chiefly for the cure of cutaneous eruptions, and are applied locally as well as drunk. They are slightly sudorific and diuretic, andare apt to occasion in some patients headach of short duration, directly after they are drunk. They are also employed for curing visceral and scrofulous obstructions, torpor of the intestines, and some dyspeptic and hypochondriacal cases.

5.' Saline Mineral Waters owe their properties altogether to saline compounds. Those which predominate, and give their character to the waters of this class, are either,

1. Salts, the basis of which is lime;

2. Chlorides of sodium and magnesium;

3. Sulphate of magnesia;

4. Alkaline carbonates; particularly carbonate of soda.

They are mostly purgative, the powers of the salts they contain being very much increased by the large proportion of water in which they are exhibited. The most celebrated saline springs are those of Cheltenham, Leamington, Bristol, Kinalton, Pancras near London, Scarborough, Sydenham, and Thursk in Yorkshire, in England; Pitcaithly, in Scotland; and Seidlitz on the Continent. They are employed in diseases which require continued and moderate intestinal evacuations; such as dyspepsia, hypochondriasis, chronic hepatitis, jaundice, and strumous swellings. They are more grateful to the stomach when carbonic acid also is present; and when they contain iron, as in the case of the Cheltenham spring, their tonic powers, combined with their purgative qualities, render them still more useful in dyspeptic complaints and amenorrhoea.

To this class the water of the ocean belongs. The quantity of saline matter Sea Water contains varies in different latitudes; thus, between 10° and 20° it is rather more than 1/24th; at the equator it is 1/25th; and at 57o north it is only 1/27th. The saline ingredients, in 10.000 parts of sea water, according to the last analysis of Dr. Murray 1, are, chloride of sodium, 220.01; chloride of calcium, 7.84; chloride of magnesium, 42.08; and sulphate of soda, 33.16. When brought up from a great depth, its taste is purely saline; but when taken from the surface it is disagreeably bitter, owing, perhaps, to the animal and vegetable matters suspended in it. Its specific gravity varies from 1.0269 to 1.0285; and it does not freeze until cooled down to 28.5° Fahrenheit. Its medicinal properties are the same as those of the saline purging waters, but more powerful; and as a bath, its efficacy is much superior to that of fresh water.

The general effects of mineral waters are modified by temperature, whether they be taken internally, or be externally applied. In some springs, as those of Bath, Matlock, Buxton, Wildbad in Germany, Bagnols in France, Bonnes in the Lower Pyrenees, Borset near Aix-la-Chapelle, Canteries in the Upper Pyrenees, Digne in the Lower Alps, Klintschysela in Russia, Lucca in Italy, Plombieres in Lorraine, and Pontgibault in France 2 : their virtues depend almost altogether on temperature; and in others, as Malvern, which has been found to contain scarcely any foreign matter, the simple diluent power of the pure water seems to produce the benefit that results from drinking them. Some of the good effects of all of them, however, must be allowed to proceed from change of scene, relaxation from business, amusement, temperance, and regular hours; and in these circumstances, the drinking the waters at the springs possesses advantages which cannot be obtained from artificial waters, however excellent the imitations may be; nor even from the natural waters, when bottled and conveyed to a distance from the springs.

1 Edinburgh Transactions, vol. viii. p. 205. The water was taken from the Frith of Forth, and was of the specific gravity 1.029.

2 See, for a very full table of mineral waters, Dr. Ryan's Essay on the Nat. Hist, of Water: Med. and Phys. Journ. vol. liv. pp. 452-461.

Table Of The More Celebrated Mineral Waters, Showing The Ingredients Contained In Each Water

Such are the known contents of the most celebrated mineral waters. Many-more have been analysed, but it is unnecessary to introduce an account of them in this place; and I consider it to be of more importance to describe the method of determining the nature and proportion of the substances, or the analysis of mineral waters, one of the most difficult parts of practical chemistry.