ARTICLE II.

An Analysis of the Mineral Waters of Dunblane and Pitcaithly; with General Observations on the Analysis of Mineral Waters, and the Composition of Bath Water, &c. By John Murray, M.D. F.R.S. E.

(Read to the Royal Society of Edinburgh, Nov. 20, 1814.)

I PROPOSE to submit to the Society the analysis of a mineral water of the saline class, which has lately been discovered in the neighbourhood of Dunblane. The subject may have rather more interest than usually belongs to researches of this nature, from the composition of this water being such as promises to afford a spring of considerable medicinal efficacy, and from its resemblance to another mineral water of some celebrity-that of Pitcaithly, the analysis of which I have, from this circumstance, been also led to undertake. The investigation, too, may afford some illustrations of the different methods that may be employed in the analysis of waters of this class, and of the facility and precision which are given to these researches, by the results that have been established with regard to the definite proportions in which many bodies combine, and the uniformity of the relations which thus exist between the compounds they form. And it has led to some views with regard to the constitution of mineral waters of the saline class, which I have applied to the composition of some of the most celebrated mineral waters. In performing the principal experiments on the Dunblane water, I had the advantage of Mr. Ellis's co-operation.

1.-ANALYSIS OF THE DUNBLANE WATER.

This water was discovered last summer, and was first taken notice of from the circumstance of the frequent resort of flocks of pigeons to the ground where it breaks out. It appears in two springs, at the distance of nearly half a mile from each other, in a field about two miles to the north of Dunblane, the property of the Earl of Kinnoul. This district is at no great distance from the range of the Grampians, to which it ascends; masses of the primitive rocks are spread over the surface, and are found in the beds of the streams; among which the conglomerate rock that seems to skirt the Grampians is abundant. The prevailing rock of the district itself is the red sand-stone, and it is generally covered by a bed of gravel, in many places of considerable depth. It is from this sand-stone that the water appears to issue. The spring, however, in both the places where it breaks out, has been laid open only to the depth of two or three feet from the surface, and has not been traced to any extent. Its proper source is therefore unknown, and it also remains uncer

tain how far it may be diluted with water from the surface, or from other springs. The water from the lower, or what for distinction may be named the south spring, is weaker in taste than the water of the north spring; and from the subsequent experiments is proved to contain rather less foreign matter. The ingredients, however, are the same; and the difference therefore probably arises from the water of the lower spring being farther diluted in its course. This difference led to the analysis of the water' of both springs. It is proper to remark, that both have been submitted to examination after a season unusually dry.

Analysis of the Water of the North Spring.

The taste of this water is saline, with some degree of bitterness. As procured from the principal pool at which it issues, it is free from smell; procured, however, from some other pools, at the distance only of a few feet, its smell is slightly sulphureous, probably owing to impregnation from matter at or immediately underthe soil. Its sensible operation on the system is that of a diuretic and purgative. The former effect is usually obtained when a quantity is taken by an adult, from an English pint to a quart; the latter, when more than a quart is taken. The specific gravity of the water is 1.00475. It suffers no change in its sensible qualities from exposure to the air.

The state of the spring is at present such, that any gaseous impregnation of the water cannot be determined with precision. Bubbles of air frequently rise from the bottom of the pool, but this is merely atmospheric air: transmitted through lime-water, it pro-` duced no sensible milkiness; nor does the water appear to contain any free carbonic acid.

The usual re-agents present with the water the following appear

ances:

1. The colours of litmus, violet, and turmeric, are not sensibly affected.

2. Muriate of barytes produces an immediate turbidness, and rather copious precipitation, which is very slightly, if at all, removed by nitric acid.

3. Nitrate of silver gives a very dense and abundant precipitate. 4. Water of potash produces a turbid appearance, not very considerable.

5. Carbonate of potash throws down an abundant precipitate, which disappears with effervescence on adding nitric acid.

6. Lime-water causes no change.

7. Ammonia does not cause any precipitation, nor does it even impair the transparency of the water.

8. Oxalate of potash, or of ammonia, occasions a copious precipitation.

9. Tincture of galls has no immediate sensible effect; but after an hour or two a purplish tint is exhibited, which deepens from exposure to the air, and inclines to olive-green.

VOL. VI. N° IV.

R

These results establish the following conclusions:

Exper. 1, proves that no free acid or alkaline matter is present, nor any alkaline carbonate.

Exper. 2, denotes the presence of sulphuric acid.

Exper. 3, indicates the presence of muriatic acid.

From Exper. 4 and 5, may be inferred the presence either of lime, or magnesia, or both.

Exper. 6 and 7, prove that magnesia is not present, nor argil. Exper. 8, proves the presence of lime.

Exper. 9, indicates a minute portion of iron.

The saline taste of the water, and the precipitation so abundant by nitrate of silver, render probable the presence of muriate of soda, and it is accordingly obtained, when the water is evaporated nearly to dryness, cubical crystals of it forming in the saline liquid.

From the whole, therefore, the principal ingredients of this water may be inferred to be muriates of soda and lime, with a smaller portion of a sulphate, and a minute quantity of iron. These conclusions suggested the following method of analysis.

An English pint of the water was evaporated to dryness; and the solid residuum was exposed to a heat approaching to redness, until it became perfectly dry. It weighed while warm 47 grains. It quickly attracted moisture from the air, so that its surface soon became humid; and on leaving it exposed for 24 hours, a considerable portion was dissolved, forming a dense liquor, while a portion remained undissolved.

The whole solid matter, being rendered dry, was submitted to the action of alcohol, with the view of separating by solution the muriates of soda and lime, of which it was supposed to be principally composed. It is well known that this method is liable, in some degree, to two sources of error; the one, that a little muriate of soda is dissolved by the alcohol with the muriate of lime; the. other, that even when a large quantity of alcohol is employed, the undissolved muriate of soda retains a small portion of muriate of lime. In estimating the quantities from the results, these errors, indeed, in some measure counterbalance each other; but still they may exist in different degrees, according to the quantity and strength, of the alcohol, and it is necessary therefore to obtain perfect precision, to obviate them as far as possible.

With this view the entire matter was digested with repeated portions of alcohol, of the specific gravity of 836, until about six times its weight had been employed; the solvent action being aided by frequent agitation, and an occasional heat of about 100°. It was then lixiviated with a small portion of distilled water, to remove more effectually from the muriate of soda any adhering muriate of lime. The different liquors, being mixed, were evaporated to dryness; and this dry mass was again submitted to the action of alcohol, more highly rectified, (being of the specific gravity of 825,) and in smaller quantity, so as to dissolve only that part of it which was muriate of lime. A small portion of muriate of soda,

which had been dissolved in the first digestion, was thus obtained, and was added to the residue of that operation. The whole undissolved matter being dried at a low red heat, weighed while warm 28.5 grains it was in small grains, having a taste purely saline. The alcoholic solution afforded, by evaporation, a matter which entered into fusion, and which, after being dried at a heat approaching to redness, weighed while warm 18-2 grains. It was highly deliquescent, so as to increase quickly in weight, and in a short time became humid on the surface.

These two products were evidently principally muriate of soda and muriate of lime. But it was necessary to ascertain if they were entirely so, as both of them might contain small portions of other ingredients.

The matter dissolved by the alcohol, supposing it to be muriate of lime, would require for its conversion into sulphate of lime about 16 grains of sulphuric acid of the usual strength: 18 grains were added with a small portion of distilled water, and heat was applied; vapours of muriatic acid were discharged: to render the mutual action more complete, small portions of water were successively added, the soft mass being frequently stirred; and when the vapours had ceased to exhale, the heat was raised to redness, to expel any excess of acid. The dry matter weighed 22 grains, precisely the quantity that ought to be obtained from 18 grains of muriate of lime.

It was diffused in a quantity of water, which it at first absorbed with a hissing noise. The water, after having been added in successive quantities, with frequent agitation, being poured off, the undissolved matter was dried at a low red heat: it weighed 18.5 grains, and formed a soft white powder, free from taste. The water poured off was very slightly acidulous. This was neutralized by ammonia; it was then evaporated to dryness, and the solid matter was heated to redness. On again submitting it to the action of a small quantity of water, a portion remained undissolved, which weighed when dried 2 grains.

There were thus obtained 20.5 grains of sulphate of lime, a quantity equivalent to 167 of dry muriate of lime. The small portion of liquor which remained in the last operation had a bitterish taste: by spontaneous evaporation, it formed acicular crystals; diluted with distilled water, it became slightly turbid on adding oxalate of ammonia, and more so on the addition of alcohol; but in the latter case, the transparency was restored on adding water. With minute portion, therefore, of sulphate of lime, it appeared to be principally sulphate of soda, derived from a little muriate of soda, which, notwithstanding the precautions that were employed, had adhered to the muriate of lime.

The matter which remained undissolved by the alcohol weighed, it has been stated, 28.5 grains. It remained to ascertain if it were entirely muriate of soda.

Being agitated with about half an ounce of distilled water, the

greater part was dissolved. The portion which remained undissolved, after being washed with small quantities of distilled water, and dried, weighed 2-4 grains. To this matter a little diluted nitric acid being added, a slight effervescence was excited: a thin crust, too, adhered to the sides of the small glass globe in which the last stage of the evaporation had been performed, which was dissolved with effervescence by a weak acid. The quantity of carbonate of lime thus indicated may be estimated at 0.5 grain. The remainder of the undissolved residue being washed and dried, was heated with two or three drops of sulphuric acid, and was thus rendered soluble in water. When neutralized by ammonia, the solution became milky; but its transparency was restored by adding more water; it became quite turbid on adding oxalate of potash, and a precipitate was thrown down by alcohol. It was therefore sulphate of lime. Its quantity may be stated at two grains.

The solution had a taste purely saline. The test of oxalate of ammonia, however, showed the presence in it of a small quantity of lime; the addition of the oxalate was therefore continued as long as any precipitation took place, and the precipitate was collected and dried. It weighed 13 grain. This production of oxalate of lime evidently arose from the presence of a small portion of muriate of lime, which, notwithstanding the precautions that had been employed, had adhered to the muriate of soda. Supposing that this had not escaped the action of the alcohol, but had been dissolved by it, and in the subsequent stage of the experiment, been converted into sulphate of lime, it would have increased the quantity of this sulphate about 1-2 grain, making it therefore 21.7, equivalent to 17.6 grains of dry muriate of lime, which the pint of water contains.

The solution contained also a minute quantity of sulphuric acid; for after removing any slight excess of oxalic acid that might have been present, it still gave a precipitate on the addition of muriate of barytes. Supposing this, as well as the rest of the sulphuric acid, to have existed in the water in the state of sulphate of lime, it will increase the quantity of that ingredient (calculating from the weight of the precipitate of sulphate of barytes obtained), from the two grains formerly noticed to 2.9.

There appeared now to remain nothing but pure muriate of soda. The solution by slow evaporation afforded that salt in cubical crystals, which, dried at a low red heat, weighed 24.5 grains. Allowing O'8 of this as the portion of product formed by the action of the muriate of barytes, it leaves 23.7 grains. And if to this be added one grain, as the equivalent of the small portion of sulphate of soda, already noticed as formed by the action of the sulphuric acid on the muriate of soda adhering to the muriate of lime after the operation of the alcohol, it gives the quantity of muriate of soda at 24.7 grains.

From these results, the solid ingredients in a pint of this water appear to be,