Читать книгу Pharmacologia онлайн

181 страница из 211

A TABULAR VIEW OF THE DIFFERENT SPECIES OF URINARY CALCULI. Species of Calculi. EXTERNAL CHARACTERS. CHEMICAL COMPOSITION. REMARKS. 1. Lithic or Uric. Form, a flattened oval; Specific gravity, generally exceeds 1·500; Colour, brownish or fawn-like; surface smooth, texture laminated. It consists principally of Lithic Acid; when treated with nitric acid, a beautiful pink substance results. This calculus is slightly soluble in water, abundantly in the pure alkalies. It is the prevailing species; but the surface sometimes occurs finely tuberculated. It frequently constitutes the Nuclei of the other species. 2. Mulberry. Colour, dark-brown; texture, harder than that of the other species; Sp. grav. from 1·428 to 1·976. Surface, studded with tubercles. It is Oxalate of Lime, and is decomposed in the flame of a spirit lamp, swelling out into a white efflorescence, which is Quick-lime. This species includes some varieties which are remarkably smooth and pale coloured, resembling a hemp seed. 3. Bone Earth. Colour, pale brown or gray; surface smooth and polished; structure, regularly laminated; the laminæ easily separating into concrete crusts. Principally Phosphate of Lime. It is soluble in muriatic acid. 4. Triple. Colour, generally brilliant white; surface uneven, studded with shining crystals; less compact than the preceding species; between its laminæ, small cells occur, filled with sparkling particles. It is an Ammoniaco-magnesian phosphate, generally mixed with phosphate of lime; pure alkalies decompose it, extricating its ammonia. This species attains a larger size than any of the others. 5. Fusible. Colour, greyish-white. A compound of the two foregoing species. It is very fusible, melting into a vitreous globule. 6. Cystic. Very like the Triple Calculus, but it is unstratified and more compact, and homogeneous. It consists of Cystic Oxide; under the blow-pipe it yields a peculiarly fetid odour. It is soluble in acids, and in alkalies even if they are fully saturated with carbonic acid. It is a rare species. 7. Alternating. Its section exhibits different concentric laminæ. Compound of several species, alternating with each other. 8. Compound. No characteristic form. The ingredients are separable only by chemical analysis.

Let us now inquire into the circumstances under which the several substances enumerated in the foregoing table, are found to be deposited; and first of the Lithic acid Diathesis. It has been already stated, that the lithic acid exists in the urine in combination with ammonia, so as to be held in solution under ordinary circumstances; if however any free acid be generated, the lithic acid is immediately precipitated, giving rise to the appearance so well known under the name of red gravel; from this view of the subject the lithic acid deposite must be considered as arising, not from the excess of that substance in the urine, but from a decomposition of the compounds into which it enters by the agency of a free acid. M. Majendie is therefore incorrect in attributing its appearance to the quantity of azote in the ingesta; an opinion which has been very ably controverted by Dr. Philip, in a paper published in the sixth volume of the Medical Transactions. It appears, moreover, that whatever tends to disturb the process of digestion, by favouring the production of acid, may be considered as the exciting cause of the lithic deposites; especially where the cutaneous functions are imperfectly performed; for Dr. Philip is of opinion, that the precipitating acid, in a healthy state of the system, is thrown off by the skin; and he supposes that even when generated in excess, it may be diverted to the surface of the body by merely increasing the insensible perspiration. The medical treatment of the lithic diathesis is thus rendered simple and satisfactory; and if the opinion of Dr. Prout be true, that at least two-thirds of the whole number of calculi originate from lithic acid, the extreme importance of the subject is too apparent to require comment. Remedies, medicinal and dietetic, that are capable of correcting dyspeptic symptoms, such as slight bitters,^[201] will doubtless prove valuable resources; while all those agents which have a tendency to correct and regulate the insensible perspiration, will necessarily fall under the head of anti-lithic remedies. Mr. Copland Hutchison, in a paper which has been published in the Transactions of the Medico-Chirurgical Society, has shewn a comparative rarity of calculous disorders in British seamen. Can the quantity of muriate of soda taken with their food, from its stimulating influence upon the cutaneous functions, be considered as affording a plausible explanation of this fact? The Phosphatic Diathesis seems to be accompanied with considerable derangement of the chylo-poietic viscera, and Dr. Prout very justly remarks, what I have frequently observed, that the stools are extremely unnatural; as the phosphates are retained in solution by an excess of acid, it would appear as if an alkaline principle was occasionally developed, and it is not unreasonable to suppose that this may be sometimes derived from bilious regurgitations;^[202] in some cases, the alkali is derived from the spontaneous decomposition of urine itself, especially where the bladder has lost its governing power,^[203] as from some injury^[204] of the spine; or from some local affection of the bladder or prostate gland; wherever the urine undergoes an incipient process of decomposition, ammonia will be generated, and an ammoniaco-magnesian phosphate^[205] be immediately precipitated: hence in cases where the bladder is unable to discharge its contents, this deposite is very apt to take place, as in diseases in the prostate; and this explains the reason why the triple phosphates are so frequently formed in elderly people, who cannot wholly evacuate their bladder.