Notes on physiology / by Henry Ashby.

  • Henry Ashby
Date:
1889
Catalogue details

Licence: Public Domain Mark

Credit: Notes on physiology / by Henry Ashby. Source: Wellcome Collection.

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    chloric acid. The precipitate is re-dissolved in potass and re-precipitated by acid. From urine.—By acidulating with hydrochloric acid, and allowing to stand for twenty-four hours, reddish crystals of impure uric acid being precipitated (fig- 2). Properties.—Pure uric acid is a white crystalline powder, almost insoluble in cold water, insoluble in alcohol and ether. The crystals vary in shape, but are for the most part of a rhombic form. It is di- basic, and combines with bases to form soluble salts, as the urates of ammonium, potassium, and sodium. By oxidation, uric acid yields : In presence of acids, alloxan and urea; in presence of alkalies, allantoine and carbonic acid. Uric acid has never been formed artificially. Tests—Murexide test.—A small portion of uric acid is moistened with strong nitric acid, and evaporated at a gentle heat. It effervesces, and leaves a reddish colouration, which on adding ammonia becomes purple. Schiff^s test.—Uric acid is dissolved in a solution of sodium carbonate; and dropped on paper moistened with silver nitrate a brown stain is formed. Hippuric acid, C9H9NO3, occurs in small quan- tities in the urine of man and carnivora, but abun- dantly in the urine of herbivora ; in the latter it is the chief means of passing N out of the body. It is precipitated by iron salts. Heated in a test-tube, it is decomposed into benzoic acid and amnionic benzoate, which condenses on the sides of the tube, and an oily substance remains behind. Most of its other salts are soluble. It crystallises in fine needles {see fig. 3). Kreatin, C4H9N3O2, exists in the muscles, and can be obtained from extract of meat. It occurs in
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