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a constituent of most, if not of all plants,* and thereby to account for the by no means unfrequent occurrence of oxalate of lime in healthy urine, we beg to observe that there are many cases of disease in which the presence of sediments of oxalate of lime in the urine cannot be in this way accounted for; and in such we are obliged to admit that the acid has been generated in the system by some deranged condition of the assimilative process.

The formation of oxalic acid in the animal system is, however, due to changes of a reverse nature to those which originate this acid in plants. In the latter reducing, in the former oxidating, processes occur. In the vegetable, oxalic acid is formed by de-oxidation of carbonic acid: in the animal, it is produced by the oxidation of some carbonaceous compound.

"The ready conversion of uric into oxalic acid, under the influence of oxidizing agents, has been satisfactorily shown by Professors Liebig and Wohler; for when uric acid is heated with water and peroxide of lead, oxalic acid, carbonic acid, and allantoin, the peculiar ingredient of the allantoic fluid of the cow, are generated. The readiness with which, under certain circumstances, uric acid is converted into the oxalic, may be well illustrated by a fact which has been observed in connexion with the guano of South America, a substance now acquiring great celebrity as a manure. This contains, when recent, a considerable proportion of urate of ammonia, which salt, after a certain length of time, often during the voyage to this country, nearly wholly disappears, and is replaced by oxalate of ammonia." 139.

Dr. Bird gives the following directions for detecting the existence of oxalate of lime deposits:

"To examine urine for the purpose of detecting the existence of the salt under consideration, allow a portion passed a few hours after a meal to repose in a glass vessel. Decant the upper 6-7ths of the urine, pour a portion of the remainder into a watch-glass, and gently warm it over a lamp; in a few seconds the heat will have rendered the fluid specifically lighter, and induced the deposition of the crystals of oxalate, if any were present: this may be hastened by gently moving the glass, so as to give the fluid a rotatory motion, which will collect the oxalate at the bottom of the capsule. The application of warmth serves, also, to remove the obscurity arising from the presence of urate of ammonia, which is readily dissolved by exposing urine containing it, to a gentle heat. Having allowed the urine to repose for a minute or two, remove the greater portion of the fluid with a pipette, and replace it by distilled water. A white powder, often of a glistening appearance, will now become visible, and this, under a low magnifying power, as by placing the capsule under a microscope furnished with a half-inch object-glass, will be found to consist of crystals of oxalate of lime in beautifully-formed transparent octohedra, with sharply-defined edges and angles." 125.

"The crystals of the oxalate, when collected in the manner above directed in a watch-glass, are unaltered by boiling either in acetic acid or solution of potass. In nitric acid they readily dissolve without effervescence. The solution may be very readily watched under the microscope. When the oxalate is allowed to dry on a plate of glass, and then examined, each crystal presents a very curious appearance, resembling two concentric cubes, with their angles and sides opposed, the inner one transparent, and the outer black, so that each resembles a trans

* Oxalate of lime constitutes nearly 50 per cent. of some lichens. Variolaria faginea, for example, contains 47.4 per cent. In such instances we may consider this salt as forming the skeleton of the plant.

lucent cube set in a black frame. This is best observed under a half-inch objectglass; as with a higher power this appearance is lost.

"In a very few cases the oxalate is met with in very remarkable crystals, shaped like dumb-bells, or rather like two kidneys with their concavities opposed, and sometimes so closely approximating as to appear circular, the surfaces being finely striated. These crystals are produced, in all probability, by a prolific arrangement of minute acicular crystals." 127.

With respect to the characters of urine containing oxalate of lime, our author observes that

"In the great majority of cases, the urine was of a fine amber hue, often darker than in health, but never presenting to my view an approach to the greenish tint described by Dr. Prout as characteristic of the secretion during the presence of what he has described as the oxalic diathesis, unless red particles of blood were present. In a few cases the urine was paler than natural; and then was always of lower specific gravity. This, however, was in most instances but a transient alteration, depending upon accidental causes. In many instances a deposit of urate of ammonia, occasionally tinted pink by purpurine, fell during cooling. This I observed to be infinitely more frequent during the months of January to March than in the three succeeding months of this year: hence it in all probability depended upon the influence of cold upon the cutaneous functions, thus causing a large amount of azote, under the form of the urate, to be excreted by the kidney. The specific gravity of oxalic urine varies extremely; in rather more than half the specimens being, however, between 1'015 and 1.025. In eighty-five different specimens of which I have preserved notes, the ratio of the densities was as follows:

In 9 specimens the specific gravity ranged from .

In 27

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1.009 1.015

1.016 1.020

1-0211-025

1.025 1.030,"

In 23

In 26

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"Many of the specimens of oxalic urine gave a precipitate with salts of lime, insoluble in acetic acid, and consisting of oxalate of lime. This, in some instances at least, depended on the presence of oxalate of ammonia, and delicate acicular crystals of this salt occasionally formed upon the edge of the capsule by spontaneous evaporation.

"The acidity of these specimens was always well marked, often far more so than in health, and never being absent. I have not yet met with a single case in which an alcaline, or even positively neutral, state existed.

"A greater increase in the quantity of urea, than the density of the urine would have led us to suspect, was frequently found; indeed, I have scarcely met with a specimen in which, when the density was above 1.015, distinct indications of an excess of urea were not met with. In twenty-four of the eighty-five specimens above referred to, so large a quantity was present, that very rapid, and in some almost immediate, crystallisation ensued on the addition of nitric acid. In general, in cases where the greatest excess of urea was present, the largest and most abundant crystals of the oxalate were detected." 131.

The following table shows the proportion of cases in which oxalate of lime was found complicated with other deposits.

"Out of the eighty-five cases before referred to

Oxalate was present unmixed in

Mixed with urate ammonia in

Mixed with uric acid

Mixed with triple phosphate
Phosphate deposited by heat.

NEW SERIES, NO. 11.-1.

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43 cases.

15

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15

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8

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85

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"In one of the specimens containing the triple phosphate, the application of heat produced a deposit of the earthy salts.

"One very constant phenomenon was observed in the microscopic examination of oxalic urine, viz. the presence of a very large quantity of epithelial scales; it was, indeed, the exception to the general rule to meet with this form of urine free from such an admixture. So constantly was it found, that repeatedly a white deposit of epithelium has often attracted my attention, and led to the suspicion of the probable presence of oxalate of lime." 132.

In no case has Dr. Bird detected sugar in urine containing oxalate of lime; and, therefore, the popular notion of the connection of this deposit with saccharine matter is unsupported by any evidence.

On the therapeutical indications for the treatment of oxaluria, Dr. Bird makes the following observations.

"The treatment, in the majority of cases, is very successful; a few only resisting all the plans which were adopted. As a general rule, the functions of the body, where obviously imperfect, should be corrected, the general health attended to by the removal of all unnaturally exciting or depressing influences, the skin should be protected from sudden alternations of temperature by a flannel or woollen covering, and the diet carefully regulated. This has generally consisted of well-cooked digestible food, obtained in about equal proportions from the animal and vegetable kingdom; all things which tend to produce flatulence being carefully avoided. The drink should consist of water, or some bland fluid, beer and wine being excluded, especially the former, unless the patient's depression render such positively necessary. A very small quantity of brandy in a glass of water has generally appeared to be the most congenial beverage at the meals. The administration of nitric acid, as suggested by Dr. Prout; or what appeared to be preferable, the nitro-hydrochloric acid, in small doses, in some bitter infusion; or, laxative mixture, as the mistura gentianæ comp., was, with minute doses of mercury, generally successful, if continued a sufficient length of time. In cases where these failed, active tonics, especially the sulphate of zinc, and where the patient was anæmiated or chlorotic, the salts of iron in very large doses, appeared to be of great use, by subduing the irritable state of the nervous system. The shower-bath, by acting in a similar manner, has been also of great service. There is one remedy which appears to exercise a marked influence over the characters of the urine, and which, from the small amount of experience I have had with it, seems to hold out the probability of its great utility in the disease under consideration: I allude to the colchicum, which, it is now generally admitted, exerts an immense influence over the organic system of nerves, and the functions under its control. The character of the urine is remarkably influenced by this drug, an excess of uric acid generally being present during its administration; and in two cases, in which oxalate of lime existed in abundance before its employment, uric acid appeared after a few days as a deposit, and nearly entirely replaced the oxalate; a circumstance generally observed during the successful treatment of this disease by other remedies. In no case have I seen the disease suddenly yield; it has generally slowly disappeared pari passu with the decrease in number and size of the crystals of the oxalate." 144.

If the views we have advocated be correct, a larger amount of animal food is indicated than Dr. Bird recommends.

CHAP. VIII. Chemical Pathology of the Earthy Salts.-Under this head Dr. Bird examines deposits composed of phosphate of lime, ammonio-phosphate of magnesia, carbonate of lime, and silicic acid. The two latter substances are comparatively unimportant. Carbonate of lime some

times occurs in small quantities in deposits of earthy phosphates when the urine is alkaline, and probably owes its origin to the decomposition of the earthy phosphate by carbonate of ammonia. Silicic acid is so rare that many writers doubt its existence in the urine.

Deposits of the earthy phosphates are always white, unless coloured with blood. They are soluble in hydrochloric acid and are insoluble in ammonia or liquor potassæ. Nor are they soluble in the urine by heat. Phosphate of lime occurs as an opake amorphous powder. The triple phosphate (phosphate of magnesia and ammonia) forms a crystalline deposit called white gravel. The neutral triple phosphate (HO, NH⭑O, MgO, P2 O') occurs in prisms, stellæ, and penniform crystals. The prisms are well defined with sharp and well defined angles and edges. The basic triple phosphate (NH+O, 2 MgO, P2 O5) occurs in stellar and foliaceous crystals.

With respect to the pathological indications of the phosphates, Dr. Bird justly observes that

"The occurrence of deposits of the earthy phosphates in the urine, must be regarded as of serious importance, always indicating the existence of important functional, and too frequently, even of organic mischief. One general law appears to govern the pathological development of these deposits, viz. that they always exist simultaneously with a depressed state of nervous energy, often general, rarely more local, in its seat. Of the former, the result of wear and tear of body and mind in old people, and of the latter the effects of local injury to the spine, will serve as examples. It is true, that in the majority of these cases there is much irritability present, there is often an excited pulse, a tongue white on the surface and red at the margin and tip, with a dry, often imperspirable, occasionally hot skin. Still it is irritability with depression, a kind of erythism of the nervous system, if the expression be permitted, like that observed after considerable losses of blood." 176.

Our author recognises at least four different pathological conditions connected with deposits of the earthy phosphates.

"A. Cases in which dyspepsia, with some febrile and nervous irritation, exists independently of any evidence of antecedent injury to the spine.

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B. Cases characterised by high nervous irritability, with a varying amount of marasmus, following a blow or other violence inflicted on the spine, but without paralysis.

c. Cases in which the phosphatic urine co-exists with paraplegia, the results of spinal lesion.

D. Cases of diseased mucous membrane of the bladder." 192.

The treatment of the first class of cases must be rather directed by general principles than limited to the solution of the phosphatic deposits. "It is true that by the persistent administration of acids the deposit may disappear for a time, but the ailment goes on; all that is effected by such treatment is to mask a symptom, and an important one, of the progress of the malady. After having attended to the morale of the case, as far as possible rousing the patient from any morbid influence excited in his mind, whether real or imaginary; the next thing is to attend to the general health. The bowels should be freed from any unhealthy accumulation by a mild mercurial laxative, as a few grains of pil. hydrarg., followed by a dose of rhubarb or castor-oil; but all active purging should be avoided, as it generally aggravates the distress of the patient, and decidedly interferes with the success of the treatment. A combination of a toniclaxative with a sedative may then be administered, as tinct. hyoscyami et sp. ammon. aromatici āā xx-3ss. ex mist. gentianæ co. 3j. ter in die. If the

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bowels be irritable, the inf. cascarillæ, or inf. serpentariæ, may be substituted for the mist. gentianæ comp. Should gastrodynia exist, great relief will be obtained by the administration of half a grain of oxyde of silver, made into a pill with confection of opium, before a meal. The diet should be very carefully regulated, all bland nutritious articles of food being preferred; vegetables should be avoided, and in general a small quantity of good sherry may be allowed. By a plan of treatment of this kind, the patients generally do well, and the phosphates and excess of urea vanish from the urine. As the patient approaches convalescence, much good is often effected by the use of sulphate of zinc in gradually increasing doses, beginning with a grain thrice a day, made into a pill with a little ext. hyoscyami, or ext. gentianæ, and increasing the quantity every three or four days, until five grains or more are taken at a dose. Under the use of the zinc, I have seen many cases do well, whose symptoms approached in severity and character those of mild delirium tremens. I need hardly say that change of scene and occupation are important adjuvants to our medical treatment." 194.

The second class of cases are far less amenable to treatment.

"In these, the phosphatic deposit is often copious and sometimes consists nearly exclusively of phosphate of lime; the lumbar pain and weight are considerable, the skin often dry and scarcely perspirable; in some cases, indeed, I have seen it look as if varnished; the tongue sometimes white, is often red; the thirst often great; indeed, the general appearance of the case closely resembles one of diabetes. The urine is generally more copious than natural, frequently pale, and of a specific gravity below the average. On investigating the patient's history, some evidence of a previous strain or wrench of the back, or a blow over the spine, is always elicited. These patients are seldom hypochondriacal; but intense irritability of temper, and a painfully anxious expression of countenance and manner, are almost invariably present.

"In the treatment of these cases, the great end and aim must be to subdue the morbidly irritable state of the brain and nervous system; and subsequently, by a generous diet and persistent use of those tonics which appear especially to exert their influence on the organic nerves, as silver, bismuth, zinc, &c., to endeavour to restore the assimilative functions to their due vigour. Besides the general indications to be fulfilled by regulated diet, amusements, exercise, &c. the use of narcotics, especially of opium, or the preparations of morphia, should be regarded as of the highest value; and we are indebted to Dr. Prout for first directing the attention of the profession to their use." 199.

Cases occasionally occur in which the symptoms are of a much milder character, but which insidiously go on to the formation of a calculus. It is in theee in particular that the use of acids is called for, to hold the phosphatic salts in solution, and prevent their being moulded into a concretion in the pelvis of a kidney. Unfortunately there is a great uncertainty attending their use; sometimes the mineral acids appear to reach the urine and destroy its alcaline character; often, however, even their continued employment appears to be utterly ineffectual in rendering the urine acid. So far as I have watched cases of this kind, the nitric acid has appeared to produce the smallest amount of gastric derangement, and to render the urine acid, or at least diminish its alcaline reaction. In one case lately, in which the nitric acid could not be borne, the phosphoric appeared to succeed." 201.

In the third class of cases, the deposition of the phosphates is a sure symptom of a grave and serious lesion, and must be treated according to the particular disease existing.

The fourth class of cases, or

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those in which the phosphates are probably entirely secreted with unhealthy mucus by a diseased lining membrane of the bladder," are familiar to every practitioner.

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