matter, so as frequently to form a complete cast of the pelvis of the kidney.

2. Where there is less disposition to form uric acid, the external laminæ are composed of the ammoniaco-magnesian phosphate, and phosphate of lime.

In one instance a small uric calculus was so deposited on the kidney, that its upper surface was exposed to a continual stream of urine, upon which beautiful crystals of the triple phosphate had been deposited. Mr. Brande therefore infers, that, under common circumstances, a stream of urine passing over a calculus of uric acid, has a tendency to deposit the phosphate upon it. II. The calculi of the urinary bladder are of four kinds: 1. Those formed upon nuclei of uric acid, from the kidney. 2. Those formed upon nuclei of oxalate of lime from the kidney.

3. Those formed upon sand or animal mucus deposited in the bladder.

4 Those formed upon extraneous bodies introduced into the bladder. These are arranged under the following divisions:First, Calculi, which from their external appearance, consist chiefly of uric acid, and which are chiefly or entirely soluble in a solution of pure potash. Secondly, Calculi composed chiefly of the ammoniaco-magnesian phosphate, or of phosphate of lime, or of mixtures of the two. These are characterized by their whiteness; by exhibiting small prismatic crystals upon their surface, and by their solubility in dilute muriatic acid. Thirdly, Calculi containing oxalate of lime, commonly called mulberry calculi. These are distinguished by the difficulty with which they are dissolved in acids, by their hardness, and by leaving pure lime, when exposed to the action of the blow-pipe.

By analysis a calculus of 60 grains yielded

Urea and muriate of ammonia

Ammoniaco-magnesian phosphate

Uric acid

Grains.

5.2

From this, and many other experiments, Mr. Brande concludes, that the evolution of ammonia depends in all instances upon the decomposition of the ammoniacal salts contained in the calculus, more especially of the ammoniaco-magnesian phosphate, and that no substance which can be called urate of ammonia exists in calculi.

By analysis it was found, that a pure specimen of the mulberry calculus consists of

III. The calculi found in the urethra consist of ammoniacomagnesian phosphate, and phosphate of lime, with a small portion of uric acid; though some appeared to consist almost wholly of ammoniaco-magnesian phosphate.

Mr. Brande, in the next section, has given the result of analysis of the calculi found in the horse, ox, sheep, rhinoceros, dog, hog, and rabbit. These were found mostly to consist of phosphate of lime and carbonate of lime in different proportions. In some, small proportions of animal matter were combined with the other substances.

The inferences drawn from these interesting and important facts are as follow:

That calculi formed in the kidneys, and immediately voided, are almost always composed of uric acid, and that the phosphates are very frequent ingredients in calculi of the bladder. They are uniformly deposited upon extraneous substances introduced into the bladder, but never form small kidney calculi. In what is commonly called a fit of the gravel, a small uric calculus is formed in the kidney, and passes along the ureter into the bladder. For some time after a stone has passed from

the kidney, the urine is generally unusually loaded with uric acid, and deposits that substance upon the nucleus now in the bladder. After this, the subsequent additions to the calculus consist principally of the phosphates.

Where the disposition to form uric acid in the kidneys is very great and permanent, the calculus found in the bladder is principally composed of uric acid; but where this disposition is weak, the nucleus only is uric acid, and the bulk of the stone is composed of the phosphates. When the increased secretion of uric acid returns at intervals, the calculus is composed of alternate layers of uric acid and the phosphates. There are besides these many variations in the formation of the calculi.

In speaking of the solvents, Mr. Brande admits, that the internal exhibition of the alkalies often prevents the formation of the uric acid, and of course an increase of a calculus in the bladder, as far as the uric acid is concerned; but that its action will not proceed any farther; because, from his experiments he finds there is at all times a quantity of uncombined acid in the urine; and hence it follows, that, although the alkali may arrive at the kidneys in its pure state, it will there unite with the uncombined acid, and be rendered incapable of exerting any action upon the calculus in the bladder. Mr. B. also observes, that whenever the urine is deprived of a portion of the acid which is natural to it, the deposition of the triple phosphate and phosphate of lime more readily takes place, which is effected by the exhibition of the alkalies; and, therefore, though alkaline medicines often tend to diminish the quantity of uric acid, and thus prevent the addition of that substance in its pure state to a calculus in the bladder, they favour the deposition of the phosphates.

With regard to the exhibition of the acids, particularly the muriatic acid, in order to dissolve the phosphates, Mr. B. admits that, during the use of this acid, the phosphates are either diminished, or disappear altogether; and even the urine acquires sometimes an additional acidity, and therefore a solution VOL. 1.

41

of that part of the calculus which consists of the phosphates may be expected; but even then the nucleus of uric acid would remain, and thus a great deal of time would be lost without any permanent advantage. He is also decidedly against the injection of these solvents into the bladder at once, by means of instruments; because, in every case that has come under his observation, it has always aggravated the sufferings of the patient. He concludes, that as the nuclei of calculi originate in the kidneys, and that of these the greater number consist of uric acid, the good effects so frequently observed during the use of an alkali arise not from any actual solution of calculous matter, but from the power which it possesses of diminishing the secretion of uric acid, and thus preventing the enlargement of the calculus; so that, while of a very small form, it may be voided by the urethra.

National Institute.

Messrs. Gay Lussac and Thenard have given an account of the method which they adopted in decomposing the boracic acid. They put equal parts of potassium and pure vitreous boracic acid into a copper tube, to which a bent glass tube was fitted. The copper tube was placed in a small furnace, and the extremity of the glass tube plunged into a bason of quicksilver. As soon as the temperature was raised to 150° (Reaumur, we preзume), the mixture became suddenly red, much heat was produced, the glass broken, and almost the whole of the air in the apparatus was driven out with great force. Only atmospheric air was disengaged, and a few bubbles of hydrogen. All the potassium disappeared, although it only decomposed a part of the acid. These substances were changed by their reciprocal action into an olive grey substance, which is a compound of potash and of the basis of boracic acid. The boracic radical was separated from it by washing it with hot or cold water. That which does not dissolve, is the radical itself, which possesses the following properties: this radical is greenish brown, fixed,

and insoluble in water. It has no taste, nor any action on tincture of litmus, or on syrup of violets. Being mixed with oxymuriate of potash, or nitrate of potash, and projected into a red hot crucible, it entered into vivid combustion, of which the boracic acid was one of the products. The most curious and most important of all the phenomena produced by the boracic radical when placed in contact with other bodies, are those that it presents with oxygen. When four grains and a half of boracic radical were projected into a silver crucible covered with a jar, containing little more than a quart of oxygen, and the whole placed over quicksilver, a most rapid combustion took place, and the quicksilver rose to about the middle of the jar. The boracic radical exhibits the same phenomena with air as with oxygen, only that the combustion is less rapid. Hence it follows, that the boracic acid is composed of oxygen, and a combustible body: and that this substance is of a peculiar nature, and ought to be classed with phosphorus, carbon, and sulphur. It requires a great quantity of oxygen to change it into boracic acid, and it previously passes into the state of a black oxyd.

Operations for Carotid Aneurisms.

The operation for carotid aneurism has now been performed four times, twice by Mr. Cooper in Guy's hospital, once by Mr. Cline in St. Thomas's, and once by a Swedish surgeon. One of Mr. Cooper's cases terminated successfully, the patient now enjoying good health; the other was unfortunate, as was Mr. Cline's. We have not heard the event of the last. The unfortunate termination of the two cases was owing to circumstances unconnected with the operation.

POSTSCRIPT.

Report of the Brooklyn Committee of Health.

The undersigned Committee of Health experience the greatest satisfaction in being able to announce the entire disappearance of the fever which lately prevailed in this place.