The Essentials of Chemical Physiology for the Use of Students
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1893 edition. Excerpt: ... 72-00 Urea..., . 33-18 Uric acid..... 0-55 Hippuric acid.... 0-40 Creatinine Ovl Pigment and other organic substances. 10-00 Sulphuric acid.... 2-01 Phosphoric acid.... 3-16 Chlorine..... 7-50 Ammonia..... 0-77 Potassium. 2-50 Sodium..... 11-09 Calcium..... 0-20 Magnesium. 0-21 The most abundant constituents of the urine are water, urea, and sodium chloride. In the foregoing table the student must not be misled by seeing the names of the acids and metals separated. The acids and the bases are combined to form salts, urates, chlorides, sulphates, phosphates, &c. UREA Urea, or Carbamide, CO(NH2)2, is isomeric (that is, has the same empirical, but not the same structural formula) with ammonium cyanate (NH4)CNO, from which it was first prepared synthetically by Wohler in 1828. Since then it has been prepared synthetically in other ways. Wohler's observation derives interest from the fact that this was the first organic substance which was prepared synthetically by chemists. It may be crystallised out from the urine by a rather complicated process (see Lesson XXVI.), and it is then found to be readily soluble both in water and alcohol: it has a saltish taste, and is neutral to litmus paper. The form of its crystals is shown in fig. 40. When treated with nitric acid, nitrate of urea (CON2H4.HNO3) is formed; this crystallises in octahedra, lozenge-shaped tablets, or hexagons (fig. 41, a). When treated with oxalic acid, flat or prismatic crystals of urea oxalate (CON2H4.H2C2O4 ] H2O) are formed (fig. 41, b). These crystals may be readily obtained in an impure form by adding large excess of the respective acids to urine which has been concentrated to a third or a quarter of its...
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