Antilithics[[182]] are remedies which have the power of preventing the formation of those mechanical deposites from the urine, which give origin to calculous concretions; and may belong either to the class of Vital, or Chemical Agents.
Lithonthryptics[[183]] are those medicines which, by a chemical operation, are capable of dissolving calculous concretions.
It has been already shewn, while treating the subject of Diuretics, that certain substances, when internally administered, are capable of passing the barriers of digestion, and of entering the circulation; and that, moreover, these bodies may be again separated by the secretory vessels of the kidneys, and be ejected from the body in the urine. It cannot therefore be contended, that the urinary calculus is placed beyond the sphere of direct medicinal influence, nor can any argument, founded upon the alleged incompatibility of chemical and vital action, be fairly maintained in this case; for the urinary calculus, as well as the urine itself,[[184]] may very justly be considered as extraneous to the living body. The existence of such a class of remedies as that of Lithonthryptics being thus established, we have to consider the mode and possible extent of their operation in the different varieties of the disease, which they are thus calculated to palliate or cure. In entering upon this inquiry, it is not my intention to prosecute the subject farther than may be necessary to explain the modus operandi of the remedies in question, and in conformity with the object and plan of this work, to establish some general principles that are to direct us in their election, combination, and administration; for farther details the practitioner must consult the systematic treatises of Prout[[185]] and Marcet,[[186]] and the very able papers of Mr. Brande,[[187]] and Dr. Wilson Philip.[[188]]
The urine may be considered as one of the most heterogeneous of the animal fluids;[[189]] and since a knowledge of its composition, and that of the morbid changes of which it is susceptible, must constitute the basis of all our knowledge respecting the formation and cure of calculous affections, the following results of an elaborate analysis by Berzelius, are submitted with a view to elucidate our pathological researches.
| Animal Principles. | Water | 933·00 |
| Urea | 30·10 | |
| Lithic Acid | 1·00 | |
| Pure Lactic Acid, Lactate of Ammonia, and Animal matters not separable from these | 17·14 | |
| Mucus of the Bladder | ·32 | |
| Alkaline and Earthy Salts. | Sulphate of Potass | 3·71 |
| Sulphate of Soda | 3·16 | |
| Phosphate of Soda | 2·94 | |
| Phosphate of Ammonia | 1·65 | |
| Muriate of Soda | 4·45 | |
| Muriate of Ammonia | 1·50 | |
| Earthy Phosphates with a trace of Fluate of Lime | 1·00 | |
| Silex | ·03 | |
| 1000·00 | ||
Besides the above ingredients, which appear to be essential to healthy urine, Dr. Prout observes that in different diseases it may contain Albumen, Fibrin, and the red particles of the blood; Nitric acid; various acids, which are found to be modifications of the Lithic; Oxalic acid; Benzoic acid; Carbonic acid;[[190]] Xanthic Oxide; Cystic Oxide; Sugar; Bile; and Pus.
It will be necessary in this place to make a few observations upon the nature and habitudes of those principles, which are more immediately active in the production of calculi—
1. Urea is a principle peculiar to urine, and must be regarded as a result of the action of the kidneys upon some of the constituents of the blood, perhaps, as Dr. Prout suggests, upon its albuminous matter. For a long time it was regarded as the peculiar principle upon which the colour and other sensible qualities of the urine depended; Berzelius however has corrected this fallacy, and considers that the Lactic acid, and its accompanying animal matters, are the bodies which impart to this fluid the characteristic smell and colour which distinguish it.[[191]]
2. Lithic, or Uric[[192]] Acid. As this principle is not found in the blood, but is constantly present in healthy urine, it follows that it must be generated by the action of the kidneys. M. Majendie[[193]] has lately endeavoured to prove that its secretion depends upon the Azote received in alimentary substances, and for the following reasons, viz. 1. Azote is a component part of Lithic Acid[[194]]—2. Those persons who use a large portion of animal food, and fermented liquors, are liable to calculous disorders—3. When animals are confined to food which contains no Azote, no Lithic acid is formed—but of this anon.—Berzelius and other animal chemists have supposed that this acid exists in urine in a free state; but Dr. Prout, whose arguments appear very satisfactory and decisive, is of opinion that it is always in combination with ammonia (Lithate of Ammonia), from which however it is very easily separated by the addition of any acid, even the carbonic, in the form of a red powder. It moreover appears to be susceptible of several important modifications, with which it behoves the pathologist to be acquainted; the profession is greatly indebted to the ingenuity and industry of Dr. Prout for some very essential additions to our knowledge, respecting the habitudes of Lithic acid with different bodies.
Erythric Acid. When nitric acid diluted with about an equal bulk of water, is poured upon pure lithic acid, and a moderate heat is applied, an effervescence takes place, and the lithic acid is dissolved; if we then concentrate this solution by a gentle evaporation, we obtain transparent colourless crystals, which have been found to constitute a peculiar acid, to which M. Brugnatelli has given the name of Erythric acid.