Читать книгу Pharmacologia онлайн

177 страница из 211

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.