BONLE, in 1663, seems to have been the first who emptoyed tests to detect the substances contained ir, mi neral waters. To these there were various additions rrvi-ic by DueLos. by HIERNE, and again I)} BOYLE ill 1678. In 1707 GEoFFirov pointed out the method of p . tiring the solid ingredients by evaporation ; and in 1;26 BOULDUC employed alcohol as the means of sepa ra,mg the saline substances from their solution in the water. At this time carbonic acid, an ingredient so common in mineral waters, and which is the agent by which many of the other substances are rendered soluble, was not known. After the discovery of this gaseous fluid by Dr. IlLnex, the labours of chemists were direct ed to mineral waters, more particularly after the publi cation of the essay of BERGMAN in 1778. Since then, numerous mineral wale, s have been subjt ctecl to analysis, by BLACK, KLAPROTII, \VESTRUMB FOURCROY, and others; the result of whose labours, and the different methods of analysis used by them, were published in the works of KIRWAN and SAUNDERS, in 1800. Of late, Dr. MURRAY has brought forward a new view of the com position of these fluids, which threatens to overturn the results of the experiments of former chemists, and which has induced him to propose a method of analysis, more simple than those generally followed.
The examination of mineral v.aters, is perhaps one of the most difficult pursuits of the chemist. It requires an intimate know ledge of the action of bodies on each other, and the utmost nicety in the manipulation ; the quantity of matter on which he has to operate being so minute. In the analysis of these fluids, the various pro cesses recommended should he tried and compared, and, if necessary, repeated till they agree in their results.
The examination of a mineral water may be divided into two parts; 1st, The investigation of the physical qualities of the water, with an account of the surround ing objects; 2:1, The chemical analysis of the fluid, so as to ascertain its component parts.
Of the Physical Qualities of the Water, EV'c.
Before proceeding. to the chemical investigation of a mineral water, it is necessary to ascertain the source from which it is derived, the nature of the substances over which it has passed, and of the soil where it has its exit.
We must likewise attend to any matter which may be deposited from it. Its taste, odour, colour, and tempera ture, must be observed, and the quantity of it discharg ed in a given time, and the rapidity with which it flows, must likewise be noticed. This examination of the water ought to he performed at different times of the day, and in different seasons, both before and after rain, as the quantity of the fluid discharged, and of course its properties, vary according to the state of the weather. By the knowledge thus acquired, some in formation may be gained with respect to the nature of the water, and of the substances which ate contained in it; thus the odour and the taste point out whether it he sulphureous or contain iron, and its sparkling indicates the presence of au fluid.
Having made these observations, the next step, is to proceed to the chemical investigation of the fluid.
Of the Substances found in Mineral Waters.
The substances found in mineral waters may be di vidtd into the gaseous fluids, the acids, the alkalies, the earths, and the compound salts.
1. Atmospheric air is contained in almost all mineral lintels, the quantity however is not great, as it seldom ex( Beds the )oh of the volume of the water. It was first pointed out in those fluids by Mr. Boyle.
2 Oxygen gas was found in mineral waters by Scheele. It ext,ts m small quantity, and is never contained in the same water with sulphuretted hydrogen or the com pounds of iron.
3. Nitrogen gas was detected in the Bath waters by Dr. Priestley, in Buxton waters by Dr. Pearson, in those of Harrowgate by Dr. Garnet, and in those of Lemington Priors by Dr. Lambe.
4. Carbonic acid is a very common ingredient in mine ral water s; it was first discovered by Dr. Brownrigg in those of Pyrmont. Its quantity varies considerably, though in general it seldom exceeds that of the water. According to Higgins, however, 100 cubic inches of Pyrmont water contain 160, and, according to \Ves trutnb, no less than 187 cubic inches of carbonic acid.