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and of practical advantage in determining their selection for use in individual cases; but a more rigorous analytical inquiry into the nature of their chemical constituents, has thus far failed most signally in serving any purpose of practical good; and, on the other hand, has rather tended to raise some mineral waters to an undeserved degree of short-lived fame, and to lower others to a degree that their curative value has not permitted to be lasting. It by no means follows, that, because chemistry enables us to determine that a given mineral water is of saline character, that the degree of its efficacy on the human body can be likewise predicated from the same premises. The investigations of chemistry are still far too limited in their results, or too uncertain in their minuter details, to justify any such inference, independently of a patient observation of the effects of the different mineral waters on a large aggregate of healthy and disordered conditions. Nor need this be regarded as offering a singular exception to what obtains in other departments. Men are perhaps apt to forget that the science of chemistry is yet in its infancy; an opinion which every year serves to confirm more and more. A very few years ago it used to be said authoritatively, that sugar is the most nutritious of the articles of food; that butter and fat are likewise pre-eminently nutritious; whereas an advancing chemistry has determined that no result of organisation that does not contain nitrogen, can minister to the azotised tissues without the addition of azote, and that such aliments are, therefore, under

all ordinary circumstances, only capable of ministering to the respiratory wants of the living body. It used to be said, that because lignin and starch have apparently nearly the same composition, and seemingly consist of the same elementary substances, therefore saw-dust might be substituted for starch in the manufacture of bread, or be made to minister to the nutrition of the animal economy. Further investigation has shown, that, were this opinion so far true as to be indisputably tenable, the solubility of lignin is so much more difficult than the solubility of starch, that under no common circumstances, or to no adequate degree, could it be held capable of supplying the wants of the animal system. And to at least the same extent, must chemical conclusions, and inferences from them, as to the effects of the different mineral waters, be received guardedly, and held subject to the confirmation of a due observation of their effects on the system; or they may lead to much and most serious error. And this is not surprising, considering the question on its own merits alone. It is inferred justly, from a careful analysis, that a given mineral water contains a certain proportion of gaseous and of solid re-agents; and the elementary nature of such re-agents may be in a great measure determined, with undisputed accuracy. But no chemist can determine how these elementary substances are combined in the mineral water, nor predicate definitely, or beyond a certain point, from his researches, what are the effects of such mineral water on the animal system. He may,

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indeed, determine, from his researches into its composition, that the mineral water he has analysed will possibly exert purgative effects on the system; but he cannot determine to what extent the said water will have this effect; and it may prove to be much less or much more purgative than his analysis would have rendered probable. And, even more than this, a mineral water of undeniable power, in its effects on the system, may afford to the laborious and painstaking analyst no clue to the cause of its efficacy. The results of analysis in the case of the different mineral waters, may be fairly said to be of value, only in so far as they enable us to class them into the several heads of saline, sulphureous, chalybeate, &c.; and to be useless, and perhaps only likely to mislead, in any attempt to compare the individual mineral waters of the same class with one another, as to their respective effects on the human body.

The European mineral waters are almost exclusively interesting to the people of Great Britain, from being sufficiently accessible to invalids. The mineral waters of Germany are more resorted to than those of any other foreign country, owing, as it seems, to the rivalry, or, perhaps, it may be the jealousy, of its different sovereignties and principalities,—and, it should be added, to the energy, perseverance, and patient civility of the people; such preference not seeming to be justly referable to any intrinsic superiority possessed by the German mineral waters, either as to physical characters, or medicinal effects, over the mineral waters of the other countries of the world.

The saline mineral waters usually exercise a purgative effect on the animal economy. These mineral waters commonly owe their aperient properties to the sulphates of soda, or magnesia, or potash, and the chlorides of sodium or magnesium. In many cases, they contain a larger or smaller, an important or unimportant, impregnation of iron. In many of the mineral waters of this class, a minute proportion of iodine and of bromine has been detected, which may well be believed to influence their medicinal properties. In this country, the principal mineral waters of this class are found at Cheltenham, Leamington, Harrogate, Ashby-de-la-Zouch, Epsom, and Scarborough; the principal mineral waters of this class on the continent, being those of Seidlitz and Seydchutz, in Bohemia. Püllna likewise possesses a saline water of considerable importance. The water of Marienbad has an important alkaline as well as aperient property. Many of the alkaline and thermal waters, as those of Vichi, Carlsbad, Wiesbaden, and Baden, contain a certain amount of sulphate or muriate of soda, which would lead to an inference that they may exercise aperient effects under some circumstances, and justify their classification under this head.

Sulphureous mineral waters are likewise usually remarkable from their action as aperients. Their properties are prominently due to the large impregnation of sulphuretted hydrogen with which they are severally charged, aided by the presence of saline aperients in greater or less amount, of which chloride of sodium is commonly by far the most important. The sul

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phureous springs of Harrogate are probably the most important in the world, although labouring under the admitted disadvantage of being offered at the natural temperature, instead of belonging at the same time to the class of thermal waters, as do those of Bareges and Aix la Chapelle; of which the former is said to issue from the earth at the temperature of 113o, and the latter at 144°. The sulphureous waters of Harrogate are said to contain an impregnation of from 3 to 21 cubic inches of sulphuretted hydrogen in the gallon, whereas those of Aix la Chapelle are said to contain 133 cubic inches of this gas in the gallon. On the other hand, the sulphureous waters of Harrogate contain a much larger proportion of saline matter than those of Aix la Chapelle. Moffat, Strathpeffer, and Rothsay, situated in Scotland, are likewise remarkable for possessing springs of sulphureous water; which are said to be impregnated with sulphuretted hydrogen in much the same degree as the sulphureous springs of Harrogate; although their saline impregnation is much less considerable.

The carbonated mineral waters are chiefly valuable from their action as antacids. To this group belong the mineral waters of Selters (Seltzer), Pyrmont, Pougues, Mont d'Or, and Vichi; to which may be added, with more or less propriety, those of Spa, Carlsbad, &c. The Selters waters are stated to contain 343.8 cubic inches of carbonic acid in the gallon; the several springs of Pyrmont, from 135 to 300 cubic inches; that of Pougues, 325.9 cubic inches; those of Mont d' Or, from 4.79 to 23.95 cubic inches;