their universal truth and importance can be admitted as sufficiently demonstrated.

Dropsies have been attributed by some authors to the inactivity or obliteration of the orifices of the absorbents of the respective cavities alone; but there can be little or no doubt that, in all serious cases, the secretion of the exhalant arteries has also undergone a morbid change. With whatever other disturbances of the processes of life these diseased affections may be connected, we are totally ignorant of the general nature of such a connexion: frequently they seem to be preceded by a state of inflammation, which has sometimes been supposed to have obstructed the orifices of the absorbents by an effusion of lymph, while the exhalants have remained pervious; but frequently also there is no appearance of any affection of this kind, and sometimes mechanical pressure on the trunk, or larger branches of the absorbents, seems to afford a tolerable explanation of the occurrence of local oedema. In general dropsy, it was discovered by the ingenious and industrious chemist Mr. Cruickshank, that a portion of the serum of the blood, at least of its albuminous or coagulating part, was usually mixed with the secretion of the kidneys: and the distinction of the nature and treatment of dropsies, according to the presence or absence of this symptom, constitutes the principal subject of Dr. Blackall's work, which is deduced from a series of observations, continued for several years, on an extensive scale.

With respect to the pathological part of the investigation, our author's labours seem to have been in great measure anticipated by Dr. Wells, of whose papers, published in 1812, the Postscript contains an abstract. In the dropsy following scarlatina, Dr. Wells found much danger from inflammation of the pleura or peritonaeum: in a large proportion of cases the kidneys secreted some red blood; in many more their secretion was turbid, and in all severe cases it was coagulable by heat. In dropsy not following scarlatina, the coagulation took place in a little more than half of the cases examined; sometimes by heat only, and sometimes by the addition of nitrous acid, a test which becomes necessary where the fluid is so much diluted as to contain less saline matter than in its natural state; for in this case the addition of any neutral salt is sufficient to render the albumen coagulable by heat as usual. Anasarca and hydrothorax most commonly exhibited the coagulum; ascites less frequently. It often happened that the whole fluid exposed to heat becaine solid; sometimes softish, but sometimes quite firm: an effect which took place when common serum was added to the same secretion in a healthy state, in the proportion of one to four. From this mode of estimation it was concluded, that in one case as much as seven ounces of serum was discharged

every day. In healthy persons Dr. Wells could scarcely ever discover any traces of a similar deposition of albumen; in some chronic diseases, especially where mercury had been employed, it was more or less observable. Bark and steel were of no use where it appeared; nor were squills, digitalis, and crystals of tartar so beneficial as in other cases: the tincture of cantharides seemed, however, to be more successful. Mr. Brande found, in a case of this sort, a considerable quantity of albumen precipitated by sulfuric acid, and an almost total deficiency of urea.

The principal part of Dr. Blackall's book is filled with a minute relation of cases of dropsies of all kinds, with their treatment, and sometimes with the appearances on dissection. Besides the distinctions derived from the presence or absence of a coagulum, Dr. Blackall seems to think that a high colour, and a large portion of extractive matter, where the coagulum is wanting, denote a strength of constitution with internal obstruction, (p. 192) and require active diuretics and deobstruents; and that the opposite state of great dilution indicates a feeble and impoverished habit, and sometimes a constitution completely broken down. With respect to the treatment of dropsy where the coagulum is discover, able, his observations are more elaborate and original.—p. 277.

'Stahl remarks, that haemorrhages are cured by moderate depletion, but by the use of astringents and tonics are converted into dropsies; and our practice will be rational in dropsy itself, in proportion as we keep the spirit of this observation in our view. The loss of the serous part of the blood, which so remarkably distinguishes it, presents to us a symptom of a very debilitating kind; and our first consideration of the subject might naturally enough encourage us to attempt its cure by those remedies, which, from their effects on occasions not apparently dissimilar, are called astringents. If, however, the doctrine of Stahl is ever true in an actual inflammatory haemorrhage, it is certainly most strictly so with regard to this flux of serum. Whoever endeavours to restrain it by bark, steel, and similar remedies, will inevitably see reason to repent that attempt in an increased tension and fulness, a pulpy countenance, a cough, if there has been already none, and in worse cases a true peripneumony. The very symptom for which he has prescribed will likewise be aggravated. Experience more than enough has convinced me of the truth and importance of this observation. Not, indeed, that practitioners can be said generally to act in contradiction to it; for they have too much overlooked the appearance to which it relates, to have made its removal an object of their contemplation. But it is so common an error in practice to impute discharges to debility, and endeavour to check them by astringents, that it cannot be too much provided against.'

It appears, however, (pp. 80 and 188) that where the urinary coagulum is very loose, bark and other tonics are beneficial.

The author proceeds to recommend very strongly that great

attention

attention be paid to the signs of inflammation, not only preferring febrifuge hydragogues, but frequently employing even venesection, especially where there are symptoms of pneumonia, after mercurial courses, and in inflammatory anasarca; the firmness, copiousness, and early appearance of the urinary coagulum affording the best guide for the administration of this remedy. Purgatives in general have the advantage of obviating an inflammatory tendency; but in hydrothorax they are generally ineffectual. Half an ounce of the supertartrate of potass daily stands in the very first rank,' especially where there is much urinary sediment and coagulum; it is less appropriate where the kidneys are feeble and their secretion watery. Antimonials also seem to favour the operation of laxatives. Of diuretics, squills are the more likely to be serviceable in proportion as the coagulum is less marked, and there is less appearance of inflammation and of indigestion; they operate best in the fullest doses that can be borne, and the mixture of gum ammoniac with nitrous ether seems to afford a good vehicle for administering them (p. 66.) Cantharides, and other stimulating diuretics, our author thinks have a tendency to promote the appearance of coagulum. Tobacco seems to have some pretensions to notice; but digitalis is the most important of all diuretics where the urinary coagulum is present; in its absence, and where the fluid is pale and crude,' it seems to fail almost uniformly: (p. 297) in the hydrothorax, its powers are truly astonishing, but it ought not to be rashly mixed with other diuretics, nor with mercurial deobstruents.

Here, however, we must observe, that we have very lately been witnesses of the total failure of a full dose of digitalis in a case of hydrothorax, which was soon afterwards completely relieved by mercurials, carried to the extent of an incipient salivation, and combined with antimonial medicines. Against an over dose of digitalis, blisters on the stomach and opiates are recommended. Dr. Blackall entertains some doubts whether the tincture is equally diuretic with the infusion and the powder. He strongly insists on the efficacy of digitalis in subduing an inflammatory diathesis, and considers it as in many cases equivalent to venesection; nor is he disposed to admit the exceptions made by Withering, Maclean, and later authors, against its use, where inflammation is present. He is even inclined to believe that the blood may generally be in an inflammatory state in the dropsy of debilitated constitutions, and that digitalis may be beneficial by breaking down' its altered texture;' (p. 316) here however we fear he is venturing a little too far into groundless theory. In other states of the body, digitalis does not appear to be diuretic. (p. 317.) Broom, artichokes, and bohea tea, are cursorily mentioned; opium more favourably; and certainly the effect of this powerful medicine in diabetes would lead

us

us to expect benefit from it in many dropsical cases. Tapping and scarifications have been observed to alter the nature of the urinary coagulum; but the relief derived from these operations is scarcely ever permanent. The diet, our author thinks, has usually been too cordial and stimulant: where there is hyperuresis, he forbids fruit, and recommends soda water; with respect to thirst, he observes that it is rarely not to be gratified. In a species which seems to have been the hydrops (anasarca) cacotrophicus, in the crew of an Indiaman, the use of well fermented bread appears to have produced an almost instant cure, as an active diuretic.

Among tonics, Dr. Blackall prefers bark in young persons of sound constitution, steel in a vitiated habit, with a sallow cómplexion. Mercury, as tending to produce the appearance of a coagulum, or even of blood, is forbidden where this appearance already exists; but where the bile passes off by the kidneys, or where their discharge is only scanty and high coloured, mercury may be the most effectual remedy. Two grains of calomel every night seem to have converted an anasarca after scarlatina into a hydrocephalus internus; while on the other hand digitalis with topical bleeding has completely succeeded in curing a hydrocephalus. Mustard cataplasms quickened with oil of turpentine are recommended to be applied to the feet in this disease; and we agree with our author in thinking this remedy frequently preferable to a common blister for the relief of local affections.

A concise and comprehensive account of almost all that has been observed concerning the angina pectoris forms an Appendix to the volume. In general Dr. Blackall coincides in opinion with Dr. Parry respecting this disease, though he remarks that in some cases the term syncope appears to be inapplicable. In the treatment, he observes that its connexion with gout or rheumatism ought to be kept in view he recommends drains, especially issues in the thighs, or rather setons about the chest ; opium in large doses, and the immersion of the arm affected in hot water, have been found very useful palliatives.

We cannot agree with Dr. Blackall when he says (p. 259) that the ancients, not without much propriety, termed the natural secretion an exhalation,' and, (p. 264.) that the fine material, which lubricates internal surfaces, is not liquid, but something more volatilised.' We are utterly ignorant of any experiments of Mr. Hunter,' which can be said to prove so paradoxical a proposition. It is firmly established, by the most accurate physical experiments, that no aqueous vapour can exist under the atmosphe rical pressure at a temperature lower than 212°; and there is no vital power which has hitherto been shown, or even suspected, to exist, that can supersede this law of inanimate nature, and communicate to a watery fluid the power of remaining permanently

elastic

elastic at the ordinary temperature of the animal body. It is only in very elevated situations, where the barometer is always very low, that even Lavoisier's reasoning, respecting the possible existence of ether as a vapour within the body, could be at all admissible. We also entertain doubts of the propriety of the expressions, that the blood has been found inflamed;' (p. ii.) a severe and long continued inflammation of the blood, not connected with any corresponding affection of the internal parts.' (p. 117.) We strongly suspect that the improper use of the term inflammation' has insensibly led the author to the reasoning which follows; can we suppose it possible that such a disposition as this should be merely general? Or, is the cellular membrane in these instances' of dropsy, the seat of an obscure inflammatory process?' We see no difficulty in supposing the possibility that the disposition should be general, or that the blood may exhibit a buffy coat in dropsy as well as in inflammation; though we do not mean to insist on the probability of the fact.

Among the difficulties to be encountered by those who, like our author, are laudably employed in applying chemical tests to nosological distinctions, the complicated nature of the products to be examined, in a state of health, is one of the greatest. In illustration of this observation, we may adduce the analysis of the fluid which has been the principal subject of Dr. Blackall's investigations, from a paper of Professor Berzelius, published in the last volume of his Essays. Afh. III. 97.

These proportions are however liable to considerable variation, without actual disease; in particular the uric acid may be entirely wanting, when the perspiration has been abundant. Some of the substances here enumerated would present but little difficulty in the operation of such chemical agents as might be employed for any purpose independent of them; while it would be highly necessary to attend to the presence of others, the complicated constitution and diversified form of which have hitherto rendered their nature and properties extremely obscure and uncertain.

ART.