The first chapter gives a general description of the mechanical deposites which take place from urine, either within or without the body. They are of three kinds :-1. The pulverulent or amorphous sediments; 2. Crystalline sediments, usually denominated gravel; and 3. Solid concretions, or calculi, formed by the aggregation of these sediments. A summary account is given of the varieties of urinary gravel and calculi, with their chymical composition, chiefly extracted from Dr. Marcet's excellent essay "On the Chymical History and Medical Treatment of Calculous Disorders;" but as our readers must have been made familiar with this branch of the inquiry by many recent publications, we pass it over in order to afford more space for subjects less generally known.

The second chapter is a very interesting one. It is occupied with data, derived from the examination of different collections, showing the comparative prevalence of the different forms of urinary deposite, and the order of their succession. Upon these data are founded a series of observations illustrative of the general pathology of calculous disorders.

In common with all writers on this subject, Dr. Prout lays great stress on the universality of the lithic acid, either as the nucleus or as the body of the calculus; but he says, that it is by the examination of the alternating calculi that a true notion is to be formed of the pathology of this disease. He investigates the modes of transition, by observing the different layers in contact with each other, and appears to us to have arrived, in this way, at some very important results.

The transition from the formation of lithic acid to the deposition of the phosphates is most interesting and instructive. It takes place gradually through the lithate of ammonia, and is accompanied by the disappearance of the usual colouring principle from the urine. The transition from the mulberry calculus to the phosphates takes place through a mixture of oxalate and carbonate of lime. The next layers are found to consist of the carbonate and phosphate of lime, and still farther from the centre, the carbonate of lime disappears. The author is inclined to believe, that wherever the change takes place ex abrupto, it is presumable that some time must have elapsed between the deposition of the different matters. It is a curious and important feature in the pathology of the urinary system, that a decided deposition of the phosphates is never followed by a different deposite. The author evidently distrusts altogether the existence of what have been called compound

calculi that is, calculi where different ingredients are intimately mixed. A comparison of the different varieties of calculi shows that there are three primary and essential distinctions among them, and these the author next treats of under the denomination of the three forms of calculous diathesis. He calls them (rather quaintly to be sure) the lithic acid diathesis, the mulberry diathesis, and the phosphatic diathesis; and a separate chapter is allotted to the consideration of each.

Lithic acid diathesis.-Lithic acid is separated from the urine in two forms, amorphous and crystallized-in common language, as sediment, or as gravel. In the first form it is ia combination with ammonia; in the second, pure. An excess of lithic acid in the urine arises from simple errors in diet, unusual exercise, or any debilitating circumstances. The speculations in which the author indulges, as to the manner in which these causes act, do not appear to us very satisfactory. The important principle seems to be this; that, if imperfectly assimilated, or unnaturally albuminous matter is brought to the kidney, it does, and must, in virtue of its natural action, convert such imperfect albumen into lithate of ammonia.

Dr. Prout divides the sediments of urine into three classes: the yellow, the red, and the pink; and attaches to this a much higher degree of importance than we are inclined to think it merits. The circumstances that chiefly struck us as worthy of notice are the following:-The yellow sediments consist of the lithate of ammonia tinged by the colouring principle of the urine. They are the sediments of health, or of the slighter forms of dyspepsia. Some persons are far more liable to them than others; and this denotes a tendency in such constitutions to an excess of lithic acid and its consequences. Red or lateritious sediments consist of the same matter tinged partly by the colouring principle of the urine, and partly by the purpurates of soda and ammonia. They occur in persons of a feverish irritable habit, and in such are excitable by trifling causes. They may be observed also in gout, rheumatism, and hepatic affections. Pink sediments are characterized by being coloured wholly by the purpurate of ammonia. The presence of the purpurates is a never-failing test of the presence of feverish or inflammatory action. Pink sediments accordingly occur in all inflammations, but they appear also in a very pure form in hectic fever, chronic liver disease, and frequently in dropsy. Sediments in the urine properly belong to the sweating stage of fever. They point out that fever has existed and is going off, rather than its actual presence.

The pathology of gravel next comes under consideration. After a good detail of the symptoms attending a fit of the gravel, the author proceeds to notice the circumstances under which crystallized deposites take place from the urine, and he observes that they are of two general descriptions, natural and acquired. The tendency to them is not unfrequently hereditary." On the other hand, the disposition to generate these sediments in excess is, like gout, or rather simultaneously with gout, but too frequently acquired by indolent habits, and excess in eating and drinking. It is connected. also with certain unknown causes, by which it becomes endemic in certain districts," as for example, that of which Norwich may be considered as the centre, in which more calculous cases occur, than in the whole of Ireland or Scotland." Lastly, we are informed that renal calculi are sometimes owing to organic disease of the kidney, or parts connected with it. (Pages 130 and 183.)

After a few remarks on the prognosis in this form of disease, the treatment proper to be pursued, where a lithic acid diathesis prevails, comes under consideration. Errors in diet are, of course, to be chiefly guarded against, but we are warned that errors in quantity are of infinitely more importance than errors in quality. Where a strong disposition exists to the formation of gravel, alkalis are indicated, "but they are seldom or never to be given alone.”

"To be really useful," adds our author, "they must be conjoined with alteratives and purgatives. The pil. submur. hydrarg. comp. or a pill composed of the pil. hydrarg. and antimonial powder taken at night, and followed up the next morning with a solution of Rochelle salts and carb. of soda in a bitter infusion, may be had recourse to. A little of the same mixture may be taken two or three times a day, so as to keep the bowels fairly open; or, instead of this, a little magnesia may be taken in a glass of soda water, as often as it may be found necessary. This plan is to be persisted in for a considerable length of time, according to the severity and obstinacy of the symptoms; the alterative pill being gradually had recourse to at longer intervals, and the doses of the other medicines diminished in a corresponding manner." P. 140.

In a fit of the gravel we are directed to begin by the employment of febrifuge means, before recourse is had to stimulating diuretics; the author having seen great mischief done by a contrary system, "the sufferings of the patient aggravated, and even his life placed in extreme danger." (Page 141.) If the case is very obstinate, or suspected to be accompanied by some local disease of the kidney, we are advised to apply a galbanum plaster to the loins, or to insert an issue or seton.

The fourth chapter is chiefly dedicated to the mulberry diathesis. Our knowledge concerning it is small, but the author conjectures-1. That the formation of oxalate of lime by the kidney is connected with a distinct diathesis, excluding the existence of other diatheses. 2. That this mulberry diathesis is of the same general nature as the lithic acid diathesis. 3. That oxalic acid is here generated instead of lithic acid; and that it is actually secreted by the kidney, and not formed there, as some have conjectured, by the agency of nitric acid.

Calculi, composed of the cystic oxyd, are rare, but always exceedingly pure. Hence the author conjectures, that the cystic diathesis is more exclusive than any other, and that it does not readily pass into any other.

We have already alluded to some of the author's ideas regarding the phosphatic, or earthy diathesis. On this subject he is certainly at variance with most of our approved writers on calculus. One of the principal points of difference between him and them, (more particularly Dr. Marcet and Mr. Brande) seems to be this:-The latter have long taught us that a tendency to phosphatic deposition is given by a long course of alkaline medicine, and this opinion, we are quite satisfied, has done far more to sway the practice of the present day in gravelish complaints, than any other we could name. Now upon this Dr. Prout lays no stress at all. He allows that in a few cases it may occur, but as a general principle in the pathology of earthy depositions from the urine, he considers it of no importance whatever. The real causes of this state of disease are, he says, either local or general. A large proportion of the cases are owing to some injury of the back. It is an old observation, that such injuries produce alkaline urine. Excessive fatigue, severe and protracted debilitating passions, are among the other general causes of the affection. Its principal local causes are irritations about the bladder or urethra, especially when operating for a considerable length of time. This appears to be the leading feature in Dr. Prout's views of the phosphatic diathesis. It is certainly deserving of remark, that the same view of the subject had long ago been taken by Mr. Murray Forbes, who expressly states, that "when a foreign body gets into the bladder, it would operate by irritation, so as to occasion a redundancy of the phosphates."

Phosphatic deposites from the urine are sometimes amorphous, sometimes crystallized. One of the characteristics of this diathesis is, that the urine, on standing for a short time, exhibits the appearance of an iridescent pellicle, con, sisting of minute crystals of the triple phosphate.

In such a condition of the urine, the indications of cure are-1, to lessen the irritability of the system by narcotics, and especially by opium, in large and repeated doses; 2, to restore the general health by tonic, and other appropriate remedies. He particularly recommends the mineral acids, uva ursi, bark, and chalybeates. Purgatives, he says, should here be used with great caution, except in children, and those slighter cases where the strength of the system is not much diminished. This may be judged of, by the specific gravity of the urine being in such cases comparatively high.

"In mild incipient cases, I have seen the greatest advantage from the combined use of the muriatic acid, hyoscyamus, and uva ursi; conjoined with the use of alterative purgatives." 162.

In opposition to the French writers, Dr. Prout is not disposed to lay any great stress on diet in a case of phosphatic diathesis. He considers the quiet of mind of the patient of far more consequence, and urges forcibly that

"Absence from care, the exhilarating air of the country, and such exercises as are consistent with the patient's condition, will perhaps more than any thing else, contribute to the cure, particularly in the slighter cases, and when the cause is not local injury." 163.

The next subject which engages the attention of the author is that of calculi, considered in a mechanical point of view; that is to say, with reference to their modes of formation and subsequent increase, the symptoms which they produce as solid foreign bodies in the different urinary passages, and the medical treatment to be adopted when they are lodged in different situations.

We are not much pleased with the laboured theory which the author throws out in page 182, to account for the first formation of renal calculi, whether lithic or mulberry. His idea is that they are thrown out in a plastic hydrated state, but we cannot avoid expressing our persuasion that this speculation is unnecessary. It does not appear to us to add any thing to general pathology, and it is clearly inapplicable to practice. After noticing the treatment to be pursued in a case of renal calculus, the author is led to consider the growth of the stone, when in the bladder; and here we were struck by an observation which appears to us very questionable. We are told, (page 195,) that the laminated structure of calculi shows that their formation has been interrupted-in other words, that it has taken place at distant intervals; for, adds the author, if a calculus was constantly increasing, its texture should be homogeneous. He afterward compares the structure of a calculus to that of an