carbon, 2,36 hydrogen, 28,27 oxygen (N1 C‍ H1O3.) Again, if we suppose the nitrogen, carbon, and hydrogen, to remain as in lithic acid, but the quantity of oxygen to be diminished to the extent of one atom, we shall have the lithic or uric oxide (xanthic oxide Marcet,) produced-(N✩ C5 H1 O2). Farther, if the nitrogen and carbon fall short, whilst the hydrogen and oxygen increase in relative quantity, we have another element of morbid urine formed, namely, cystine, (cystic oxide, Wollaston,) as appears by the composition of this substance, 11.85 nitrogen, 29.88 carbon, 5.12 hydrogen, 53.15 oxygen, (N C3 H6 O1). Another very remarkable quaternary compound, occasionally met with in morbid urine, is carbonate of ammonia, for the presence of which we should, without the lights afforded us by chemistry, be greatly at a loss to account. But when we know that the elementary composition of urea is identical with that of the cyanate of ammonia; that if one atom of this substance and one atom of water come to decompose each other, which readily happens, and that the product is exactly one atom of carbonate of ammonia, we have no difficulty whatever in explaining the occurrence in the urine of the volatile alkali combined with carbonic acid.

Occasionally, again, two of the elements of urea part company, as it were, with the other two, and enter into certain binary combinations that are also now and then detected in the urine, either alone, or accidentally conjoined with bases which they have encountered in the fluid. Thus the nitrogen and carbon uniting and separating themselves from the hydrogen and oxygen, give rise to cyanogen or bicarburet of nitrogen; and it is no less remarkable than indisputable that compounds of the cyanic acid, other than the cyanate of ammonia already mentioned, such as the ferro-cyanate of potash and even hydrocyanic acid in a free state, are sometimes met with in the urine. It farther happens not uncommonly, especially in certain febrile states of the system, that the nitrogen and oxygen select each other peculiarly, leaving out of the question the carbon and hydrogen, and form nitric acid, which, acting on the lithic acid, is the source of the compounds that have been described under the titles of the erythric and purpuric acids. Finally, if the nitrogen and hydrogen part company with the carbon and oxygen, and leave these last to unite very nearly in the proportions in which the former occurs in lithic acid, the latter in cystine, we have oxalic acid produced,-39.99 carbon, 53.33 oxygen,-an occasional and very formidable constituent of the urine in certain morbid states.

Under other circumstances, the kidney seems to fall short of the acidifying property it possesses as part of its distinguishing function, and then the radicals of the acids which the urine contains present themselves in an uncombined state. It is in this way, probably, that phosphorus now and then appears in solution in the urine, so that the fluid is seen to be luminous when emitted in the dark.

It is even possible that the albumen which often shows itself as a constituent of the urine, in a form of kidney disease that has lately attracted much attention, may be derived from the urea. Making urea the standard of comparison as before, if the relative proportion of nitrogen be considerably lessened, whilst the portions of hydrogen and especially of carbon are much increased, we have the elements of albumen, 15.56 nitrogen, 49.75 carbon, 8.77 hydrogen, 26.78 oxygen. In other cases the albuminous principle contained in the urine is unquestionably derived immediately from the blood, as is proved by the passage along with it of the fibrine red particles and other constituents of this vital fluid." 107.

The extract is long, but the facts which it expresses are exceedingly important, and no less important than clearly stated.

The chapter before us contains twelve sections. The first is on the—

Discharge of Urine, which contains the Lithic Oxyde-LITHOXIDURIA. Our readers must be aware that Dr. Marcet described a calculus under the name of xanthic oxyde. Berzelius suspected that it was no other than uric acid, accidentally modified. But Langenbeck has lately extracted a stone which, after a very careful analysis by Liebig and Woehler, has proved to be the xanthic oxyde. Its constitution was the same as that of lithic acid minus one atom of oxygen; these two substances were in fact two oxydes of the same radical, the formula of lithic acid being C5 N+ H+ O3, that of the xanthic oxyde, which they of course designate with the greatest propriety lithic or uric oxyde, being C' N4 H4 O3.

It has not been recognized either in solution or as a deposit from the urine. Dr. Willis remarks, that the lithic oxyde may be expected to occur, associated with deposites of the lithic acid. We have, in fact, but to suppose the kidney to fall somewhat short of its acidifying powers, to have the lithic oxide instead of the lithic acid (the oxide instead of the acid of urea) produced.

SECTION 2. Of the discharge of Urine which contains Cystine (cystic oxide) in solution or as a deposite-CYSTINURIA.

This, which occasionally forms calculi, has been several times discovered in urine, both in a state of solution and mechanical suspension. Dr. Frout and Dr. Venables have both described cases in which they detected it. In both calculi existed. Dr. Willis has lately found it in a case in which none could be suspected. His attention was arrested by the greenish-yellow colour of the urine, its peculiar smell, and its somewhat oily appearance when passed. It reddened litmus paper very slightly, if at all; was of sp. gravity 1.030; did not coagulate by heat or nitric acid, and by standing became opalescent after thirty-six hours from the presence of a fine pulverulent matter, part of which was deposited. Acetic acid threw down a pretty copious brown precipitate, which, collected on a filter, was found to possess all the properties of cystine. This urine held a considerable quantity of the phosphatic salts in solution, which seems common; it showed no traces of lithic acid; but Dr. W. could not discover that it was deficient in urea, though, in the previously described cases, it has been so.

The best re-agents for discovering cystine in combination with alkalis are the acetic, citric, or tartaric acid; in each of which it is insoluble. The bicarbonate of ammonia immediately throws it down from its soluble combinations with potash and soda.

M. Rayer observes that the calculi formed of cystic oxyde are agglomerations of confused, semi-transparent, yellowish, and insipid crystals. The precipitate of cystine consists of hexagonal, colourless, and transparent laminæ, visible in the microscope, when its solution in potass is treated with acetic acid, or, when dissolved in ammonia, whence the crystals spontaneously separate by evaporation.

SECTION 3.-Of the discharge of Urine, which contains the Purpuric acid,

and its Salts-PORPHURURIA.

The red colour of the sediments of febrile urine, and the pink hue of the sediment of hectic and dyspeptic urine have been ascribed by Dr. Prout to

the presence of a purpurate, either of ammonia or of soda. But Berzelius concluded that the red and pink colours of urinary sediments were not caused by the intermixture of a purpurate of any base, but by the presence either of the ordinary colouring matter of the urine, or of a peculiar animal matter, which dyed the deposites in the manner of lakes. The point is not yet settled, for, as Dr. Willis observes, organic chemistry forms the low-countries of the science, the field of all the disputes that are going.

The depth of tint of the sediment would seem to depend on the quantum of the adventitious colouring principle. Sometimes the tint exists with little

sediment.

"The dusky red or lateritious sediment, which recent observations have shown generally to consist of lithic acid combined with an animal colouring matter, is the well-known herald of the abatement of febrile and inflammatory action in the system, and is always looked for anxiously in cases of danger by the attentive pathologist. The depth of tint of the sediment let fall under such circumstances, has even been observed to afford a kind of criterion of the intensity of the symptoms, the deep dusky red sediment showing itself during and especially on the abatement of high inflammatory fever in vigorous subjects; the paler coloured and fine pink precipitates being associated with action of a less energetic kind, with the low fever of local organic disease, or hectic, as it is called. A purpuric state of the urine (without regard to the nature of the colouring principle) in a less marked degree appears to be almost habitual to certain individuals of excitable and delicate constitution, among whom slight errors of diet, exposure to cold, and even an ungenial state of the atmosphere, though no chill has been suffered, are observed to produce it. Probably the purest specimens of the bright pink sediment that are ever met with, are deposited from the urine of some dropsical subjects, and of those who are labouring under chronic visceral affections especially of the liver. There seems no reason, however, to conclude that visceral diseases are present as the causes of these pink sediments in every instance in which they occur; on the contrary, they are frequently observed accidentally in cases where there is no room even to suspect the existence of organic disease, and in which none certainly exists.

Occurring occasionally and in conjunction with obvious causes of general excitement, or of particular local derangement, a purpuric state of the urinary secretion is to be regarded as of just as much but not of more importance than accidental lithic states of this product. When it presents itself in a high degree, however, and habitually for any length of time, there are just grounds of alarm; a deranged condition of the general functions, depending in all probability on some latent organic mischief of a local nature, that may ultimately bring the patient's life into jeopardy, being indicated." 114.

There need not be said much on the subject of treatment. When an attendant on febrile excitement the remedies for the latter are usually the remedies for it. When the general features are those of the lithic diathesis, the latter becomes the subject of treatment. In short, the object is to determine the cause, organic or functional, of the affection, and to act accordingly. Pink coloured lithic deposites certainly should not be neglected. They have formed, in two instances, the nucleus of a stone.

SECTION 4.-Of the discharge of Urine which contains a Salt of the Oxalic acid,-OXALURIA.

Dr. Willis commences this Section by observing :

"Lithic acid under the prolonged action of nitric acid and of chlorine, is partly

converted into oxalic acid. Liebig and Woehler found that when lithic acid was boiled with the superoxide of lead it was resolved into urea, alantoin, carbonic acid, and oxalic acid. I have besides shown, in the general remarks introductory to the different sections of the present chapter, that the proportion of carbon which exists in lithic acid, united to the proportion of oxygen which occurs in cystine, form as nearly as may be the combining quantities of the elements of oxalic acid. I do not, therefore, find any peculiar difficulty in accounting for the occasional existence of oxalic acid as a product of the renal secretion. It does not seem necessary to suppose that this substance should be introduced among the ingesta: its elements exist in urine, and the chemic art of the kidney may, and undoubtedly does, suffice at times to combine them into the compound in question. Nevertheless it remains true that certain articles of food, which are pretty generally used in some countries, contain oxalic acid; and the experiments of Woehler have put it beyond doubt that it is one of the few acids that make their way into the torrent of the circulation, and are then eliminated both free and combined with a base from the system by the kidney. The urine contained in the bladder of a dog, killed eight hours after having had two drams of oxalic acid mixed with a quantity of meat and bread given to it, was found to deposite a precipitate on cooling, which bore an exact resemblance to that formed by the triple phosphate. The clear urine mixed with a little of a solution of nitrate of lime gave a farther deposite, having the same external characters. On examination both of the deposites were found to consist of oxalate of lime. The articles of food used by man which contain oxalic acid in largest quantity are the sorrel, (Rumex acetosa), so much eaten by all classes in France, and consumed to some extent by the upper ranks in England as an agreeable vegetable; the tomata, (Solanum lycopersicum), of which many individuals are passionately fond; and the leaf-stalk of the rhubarb plant, (Rheum palmatum,) which in the spring and early summer months is consumed in large quantities made into pies and puddings by the community at large in England." 118.

M. Rayer appears to doubt the influence of sorrel in producing oxalate deposits. Yet evidence seems in favour of the supposition. The oxalate of lime has not often been observed as a precipitate from the urine. But Mr. Henry Brett has lately published an interesting case of it. Dr. Willis thinks that when the urine is more carefully and more scientifically examined, deposites of the oxalate will be found not to be rare. It probably, however, occurs most frequently as an ingredient in amorphous urinary sediments. It has been detected in company with the amorphous lithic acid sediment-and has been confounded with the lithate of lime.

The oxalate diathesis is probably intimately connected with the lithic. On this hint the treatment is founded, for the same general plan must be pursued as is required for the latter. Those who labour under it should, of course, give up those vegetables which contain oxalic acid.

5. The next Section is appropriated to the discharge of urine, which contains albumen (as a derivative from urea ?) We shall defer what our author says of albuminous urine, until we take that up.

SECTION 6.-Of the discharge of Urine which contains the Elements of Urea in the shape of Carbonate of Ammonia.

The elements of one atom of urea, combining with those of one atom of water, constitute one atom of carbonate of ammonia, a combination which

implies decomposition both of urea and water, and occurs very readily in high temperatures.

This change, the common consequence of decomposition without, may occur in the kidney itself, from which it is directly eliminated by an altered mode of secretion. Dr. Graves was the first who demonstrated this fact. He has related two instances. The first was that of a patient labouring under bad continued fever with petechia. The urine abstracted from the bladder, which showed no signs of disease, within two hours after it had been completely emptied, was found strongly ammoniacal. The second case was that of a powerful labourer, who fell dangerously ill of fever and anasarca, from having worked up to his knees in water during cold weather. The urine here was of a pale straw colour, and deposited the phosphatic salts on standing; it smelt strongly of ammonia, and effervesced briskly on the addition of an acid, when a sample of it, obtained from the bladder within so short a time as half an hour after this viscus had been completely emptied, was examined. This patient died. The bladder was found perfectly healthy. The kidneys were enlarged, and turgid with blood. The liver was much diseased. The urine was without a trace of urea. In a case of ascites, quoted by Nysten, the urine contained much carbonate of ammonia, but no urea; and, in two cases which were under treatment for the honey diabetes in the Royal Infirmary of Glasgow, by means of animal food and opium, the urine which had been highly ureous, became suddenly alkaline, and was found to contain a large quantity of ammonia, but no urea. In these cases he combines the elements of urea so as to constitute the carbonate of ammonia.

Dr. Willis goes on to remark, that in certain irritable states of the system, when the urine is secreted copiously, and with a disposition to throw down the phosphatic salts, circumstances in which the fluid is often neutral, or acid only in the very slightest degree, any additional irritation, such as that produced by the introduction of a bougie or catheter into the urethra, will often suffice to turn it positively alkaline.

The state of the urine in typhoid fever, with regard especially to its acid or alkaline reaction, is often advantageously consulted as an index of the progress of the disease. In the earlier stages the urine is acid, and as the disease advances it becomes neutral, and then alkaline; as the disease declines, on the contrary, the urine from alkaline becomes neutral and then acid. The return to the acid state is always a favourable sign, and may sometimes enable us to give a flattering prognosis when there is nothing else in the state of the patient that betokens improvement.

We need hardly observe that ammoniacal urine can only be remedied through the system at large. To treat it is to treat the constitutional state of which it is a consequence and index. But it is important to be aware, that the urine may be secreted ammoniacal, for when this condition is observed it is usually attributed to putrefactive fermentation of the fluid in the bladder.

In certain chronic diseases of that organ we have indeed ammoniacal urine of the most offensive description evacuated. There, the ammonia seems really due to rapid decomposition of the urine effected by the putrefactive ferment of a diseased vesical mucus. In many of these cases if the bladder be carefully washed out as a preliminary, urine may be withdrawn by a clean