wards that side. The remainder of the cavity that was not occupied by the lung was filled with cellular substance.

The whole of the left lung, and small portion of the right mentioned above, were of a dark liver colour, without adhesion. On cutting into their substance, a great quantity of frothy phlegm, intermixed with a dark-coloured blood, issued out. Their whole substance seemed to be as completely filled with this fluid as a sponge well soaked in water, and it ran out in a stream, without pressure, on merely making an incision with

the knife.

The pleura costalis, except at the place of adhesion, was natural, nor was there any water in the cavities of the thorax.

The trachea appeared very vascular, and on its anterior side, within the thorax, there were, betwixt its cartilage rings, portions of imperfect rings of extravasated blood in the state of coagulation.

MEDICAL EXTRACTS.

No. IX.

An Analysis of the Mineral Waters of Dunblane and Pitcaithly ; with general Observations on the Analysis of Mineral, and the Composition of Bath Water and some others. By JOHN MURRAY, M. D. F. R. S. Edinburgh.

(See Transactions of the Royal Society of Edinburgh, Vol. VII. Part II. p. 411.)

THE

THE essay of Dr Murray deserves to be very generally studied by professional men; but very few of them can have an opportunity of reading it in the philosophical work in which it is published. We therefore feel a pleasure in being able to give it greater publicity; and only regret that its great length obliges us to omit some parts, and abridge others.

Dr Murray was led to these considerations in consequence of analysing the mineral waters of Dunblane and Pitcaithly, both in Perthshire. The very ingenious method of performing these analyses, and the curious chemical views stated in regard to the methods of analysing mineral waters in general, are highly interesting to the chemical student; but we must content ourselves with extracting the results obtained from a pint.

"It is a question not unequivocally determined, and perhaps not capable of being determined, in what state the saline ingredients of a mineral water exist,-whether the acids and bases are in those binary combinations which constitute the different neutral salts, or whether they exist in simultaneous combination, the whole acids being neutralized by the whole bases. If the former, which is the more com mon, and perhaps the more probable opinion, be adopted, it is at least certain, that the state of combination may be modified by the analytic operations, and that the binary combinations obtained by these may not be precisely those which existed in the water. In the case of the Dunblane water, for example, the ingredients obtained are muriate of soda, muriate of lime, and sulphate of lime. Now, it is possible that the sulphate of lime may be a product of the operation, not an original ingredient. The sulphuric acid may exist rather in the state of sulphate of soda, and when, in the progress of the evaporation, the liquor becomes concentrated, this salt may act on a portion of the muriate of lime, and, by mutual decomposition, form corresponding portions of muriate of soda, and sulphate of lime.

"A question of this kind is not merely one of speculation, but the solution of it may sometimes throw light on the properties of mineral waters, particularly on their powers of affecting the living system. The present affords a very good example of this. Sulphate of lime is a substance apparently inert. If it exist, therefore, as such in water, it can contribute nothing to its efficacy. But in the other state of combination which is supposed, both the quantity of the muriate of lime, the more active ingredient, will be greater, and the presence of sulphate of soda will in part account for the purgative operation which the water exerts.

"There is no very direct, and perhaps no decisive experiment, by which this question may be determined; for any method which would cause the separation of either substance as a binary compound, may also be conceived to operate by causing its formation.”

Dr Murray then gives some arguments in favour of his opinion.

"These results do not absolutely establish the conclusion, that VOL. XII. NO. 47.

X

the sulphuric acid exists in this water in the state of sulphate of soda; yet, on the whole, this is the more probable opinion. If it be admitted, the preceding statement of the ingredients, and their proportions, must be altered. The sulphate of lime is of course to be omitted. The sulphate of soda, which is to be substituted for it, cannot be obtained by any method; but the quantity of it may be inferred, from the quantity of sulphate of lime which is formed by its action on the muriate of lime. Real sulphate of lime, and real sulphate of soda, are very nearly equivalent to each other with regard to the proportions of their acid and base; so that the quantity of the one may nearly be substituted for that of the other; 3.5 of sulphate of lime being equal to 3.7 of sulphate of soda. But this sulphate of lime is formed at the expence of a portion of muriate of lime, and its formation is accompanied with the production of a little muriate of soda; hence the proportion of the former must be a little larger, and that of the latter a little smaller, than have been before stated. 3.5 grains of sulphate of lime are equivalent to 2.8 of muriate of lime, which quantity, therefore, is to be added to the proportion above assigned. The equivalent portion of muriate of soda to be subtracted is 3. The whole proportions, therefore, will be the following:

"The quantity of sulphate of lime obtained in the analysis of the Pitcaithly water, being so much smaller than that in the Dunblane, it may perhaps be considered as an original ingredient; or, if even the opposite view be adopted, the change in the proportions, as indicated by the analysis, is much less. They may be stated as follow:

Sulphate of lime has been often stated as an ingredient existing in mineral waters, with muriate of soda and muriate of lime. It is almost superfluous to remark, that it is probable the original ingredients, in all such cases, are sulphate of soda and muriate of lime, and that the sulphate of lime is a product of the operation, or rather, that the portion of it equivalent to the quantity of muriate of soda, has this origin.

"It is a curious fact, which strongly confirms this, that in almost all the analyses of mineral waters since the time of Bergman, when

they can be presumed to have been executed with any precision, where sulphate of lime is an ingredient, muriate of soda is also present. It is obvious, that, if the sulphate of lime has this origin, muriate of soda must also be formed. On the other hand, in the greater number of those analyses in which muriate of soda is an ingredient, we find also sulphate of lime; and, with the exception of the water of Harrowgate, sulphate of lime is always present, where muriate of soda and muriate of lime are conjoined.

"But the principal interest belonging to this view, is derived from its relation to a question which has often been brought under discussion,-Whether chemical analysis is capable of discovering the sources of the medicinal virtues of mineral waters? This question some have been disposed to decide in the negative, from finding examples of waters possessed of active powers, in which analysis does not detect any ingredients of adequate activity.

"On the general question, the remark by Dr Saunders is perfectly just, that, considering the comparative accuracy to which chemists are at present able to carry their inquiries, we can hardly suppose, that whatever slight error might occur in the estimation of minute quantities, the actual existence of any powerful agent on the human body, in any mineral water, should escape the nicety of research.' Yet though this is just, and though we can have no hesitation in rejecting the opinion which would ascribe the medicinal qualities of mineral waters to unknown or mysterious causes, or which would deny all power to those in which an active chemical composition cannot be discovered, difficulties on this subject undoubtedly exist, and there is some room for that scepticism which has been extended to this department of the Materia Medica.

10

"Of this no better example can be given, than the celebrated Bath water. It has always been found difficult to account for its powers, the ingredients which are obtained in its analysis being substances of little activity, and the principal ones, indeed, being apparently inert. It contains in an English pint, along with a slight impregnation of carbonic acid, about 9 grains of sulphate of lime, 3 grains of muriate of soda, 3 grains of sulphate of soda, ths of a grain of carbonate of lime, 4th grain of silica, andth grain of oxide of iron. Now, from these ingredients unquestionably no medicinal power of any importance could be expected. They are either substances altogether inert, or are in quantities so minute, as, in the dose in which the wa. ter is taken, to be incapable of producing any sensible effect. Some have from this circumstance been disposed to deny altogether any virtues to these waters; but the reverse of this appears to be establish. ed by sufficient evidence, and what is still less equivocal, the injurious effects they sometimes produce, and the precautions hence necessary in their use, sufficiently demonstrate their active powers. To account for these, therefore, various hypotheses have been proposed. The observation has been urged, which, to a certain extent, is undoubtedly just, that substances given in small doses in a state of great dilution, may, from this dilution, produce more effect on the

general system than the quantity given would lead us to expect. The temperature of the water, too, it has been supposed, may have a considerable share in aiding the effect; and these two circumstances in particular, it has been imagined, may favour the action of the iron. This is the view of the subject given by Dr Saunders, in his Treatise on Mineral Waters. Some of the other ingredients, too, it has been supposed, may exert unknown powers. Thus, some effect has been ascribed to the agency of the nitrogen gas which rises through the water. And Dr Saunders himself, apparently not very well satisfied with the reasoning he had employed, allows some weight to the opinion suggested by Dr Gibbes, that the silicious earth assists in the general effect of the Bath waters ;-remarking, that though there is only half a grain of it in a pint of the water, this forms no objection, when the great powers of very minute quantities of active substances are considered; that neither is its insolubility in the animal fluids an objection, as it exists in the water in a state of solution; and that, though it has neither taste nor smell, it may be an active substance, since there are indisputably powerful medicines, which have little of either of these qualities.

"All this, it is superfluous to observe, is extremely unsatisfactory. With regard to the iron, the only active substance, allowing full weight to the observations, that small quantities of active medicines, under great dilution, operate with increased power, and that a high temperature may aid their operation on the stomach,--still we cannot believe that one-sixtieth of a grain, the quantity in a pint of this wa ter, can produce any important medicinal effect. And, with regard to the other substances, the reasoning whence their possible operation has been inferred, instead of removing the difficulty, rather places it in a clearer light.

"The view of the constitution of mineral waters stated above, enables us to assign to the Bath water a much more active chemical composition. There is every probability that muriate of lime is its powerful ingredient. The principal products of its analysis are sulphate of lime, muriate of soda, and sulphate of soda. The proportion of sulphate of lime is such, that part of it must pre-exist in the water, but part of it, there is reason to conclude, is a product of the analysis; the muriate of soda is entirely so, and the quantity of sulphate of soda is larger than what the analysis indicates. In other words, there exist in it muriate of lime, sulphate of soda, and sulphate of lime, and, during the evaporation, the muriate of lime being acted on by a portion of the sulphate of soda, muriate of soda and a corresponding portion of sulphate of lime are formed.

"On this view of the composition of the Bath water, it is easy to assign the proportions of the ingredients, from the products which are obtained in its analysis. In the formation of 3.3 grains of muriate of soda, which is the quantity obtained from a pint of the water, 3.1 grains of muriate of lime must be decomposed: 4 grains of sulphate of soda would be required to produce this decomposition ; and, at the same time, 3.8 grains of sulphate of lime would be formed.