31. Muriate of manganese is found in some waters. According to Lambe it is contained in those of Leming ton Priors, and Dr. Scuclamore has found it in the water of Tunbridge wells.
32. Hydro-sulphuret of soda has been observed in some watt- a.
33 Hydro-sulithuret of time though exists in them.
It mus On here remarked, that the salts mentioned above, as existing in mineral waters, arc those which have been procured by the evaporation of the fluid, hence inferring, that those deposited by evaporation are the salts which the water contained. Other views are, however, entertained with respect to the state of combination of the acids and bases, which, if correct, will make the salts different from those stated.
Besides the substances enumerated, mineral waters contain animal and vegetable bodies ; these, however, arc probably accidental.
From the above statement, it would appear that a mineral water contains an immense variety of ingre dients; this, however, is not the case. A mineral water seldom contains above S or 10 of these substances ; in deed it rarely happens that the number is so great. In general it does not exceed 6. The substances most commonly found are, free carbonic acid and sulphuret ted hydrogen, carbonates of soda, lime, magnesia and iron, sulphates and muriates of soda, lime and magne sia. Owing to the waters containing some of these in gredients, while the others are wanting, or in small quantity, they have been divided into different classes, and named according to the substance which imparts to them their particular properties.
Mineral waters are divided into four classes, the aci dulous, the sulphureous, the chalybeate, and the saline.
Acidulous waters are those which contain carbonic acid in its free state, or in combination in excess with a base. These waters are easily distinguished by their slightly acid taste, and by their sparkling when poured from one vessel to another; both of which properties they lose, when exposed to the air for a length of time, or by boiling. Besides carbonic acid, they almost al ways contain muriatc of soda, and some of the earthy carbonates ; it is the free carbonic acid, however, that imparts to them their particular properties.
Sul/ihureous waters are those which contain sulphu react] hydrogen. These are very easily distinguished by their odour, and by their rendering a solution of a salt of lead black, or by causing a piece of silver, when immersed in them, to acquire a dark colour. Besides sulphuretted hydrogen, they in general contain alkaline and earthy sulphates and muriatcs. The sulphurcous waters may be subdivided into two kinds; 1st, Those which have sulphuretted hydrogen in its free state : 2d, Those in which it exists in union with an alkali or an earth.
Chalybeate waters are those which have iron as an ingredient. These are known by their peculiar taste, and by their becoming black when mixed with an infu sion of nutgalls. The chalybeate waters arc of different kinds; sometimes the iron is combined with sulphuric acid, more frequently it is in union with carbonic acid ; this may be just in sufficient quantity to hold the iron in solution, or it may be in excess, in which case, be sides chalybeate, the water possesses acid properties, forming what is called an acidulous chalybeate water.
Saline waters are those which contain the saline in gredients generally found in mineral waters, but which have not carbonic acid in excess, and are free from sul phuretted hydrogen and iron, or contain them in very trifling quantity. Saline waters may be subdivided into four kinds.
(a) Alkaline waters, or those which contain alkali in its free state, or combined with carbonic acid, and which render the vegetable blues green.
(b) Hard waters, or those which contain carbonate or sulphate of lime.
(c) Salt waters, or those in which muriate of soda abounds.
(d) Purgative waters, or those which contain princi pally sulphate of magnesia.
Of the Chemical Analysis of Mineral Waters.
In the analysis of mineral waters the first object is, to ascertain the different substances which they contain; the next is, to find out the quantity of each ingredient ; and lastly, to ascertain in what state of combination these substances exist, and what are the proportions of the different compounds which they form.