CHAPTER VI. KEY TO THE APPROXIMATIVE ANALYSIS OF URINE. After the urine has been allowed to stand for an hour, its physical characteristics should first be observed. 1. The twenty-four hours' amount. 2. Color and transparency. 3. Odor. 4. Reaction upon litmus. 5. Specific gravity. 6. Quantity of the sediment. If a sediment has formed, the urine must be poured off and made use of for the several chemical tests. If the urine is quite cloudy, it should be filtered; should it not then be quite clear, it may be advantageous to warm it slightly to render it so. The sediment is set aside for analysis. CHEMICAL INVESTIGATION. A. Nitric Acid. Take about 15 c.c. of clear urine in a wine-glass, and pour down the side of the glass a sub-layer of pure nitric acid (HNO3). We find by this 1. Albumen (p. 91); 2. Urates (p. 60); 3. Biliary coloring matters (p. 131); 4. Indican (p. 66). If the urine contains much iodine, the zone between the fluids is colored a brilliant yellow-brown. The odor of iodine is perceived distinctly (p. 145). If but small amounts of these matters are present, they appear only after a few minutes. It is well to set the glass aside, while proceeding with the following test. B. Heat Test. Fill a test-tube one third full of clear urine, and heat over a spirit lamp. If a turbidity arises, then it contains either albumen or the earthy phosphates, which are precipitated by heat. Add now one or two drops of acetic acid the earthy phosphates will be dissolved, but the albumen remains. Add now potassium hydrate in volume equal to one half that of the urine in the tube: the albumen will go into solution, and the earthy phosphates will precipitate in small flakes. Heat the mixture again : if it becomes brown, sugar is present. If it does not become brown by boiling, set the tube aside in order to allow the phosphates to settle, that their amount and color may be noted. The earthy phosphates of normal urine are white. If they appear colored, the urine may contain various coloring matters; if blood-red or dichroic, blood-coloring matters are present. As a confirmation of this, albumen must be present, and the crystals of hæmine should be tested for in the sediment of the urine which forms naturally, micro-chemically, or from the albumen coagulum tinged by the coloring matters, by means of the same test (p. 128). Also under the microscope we almost always find blood-corpuscles in the urine sediment. If the earthy phosphates appear rose-red, and there is no albumen present, plant-coloring matters are indi cated (p. 127), especially after the internal use of rhubarb and senna. As a confirmatory test we add ammonia to the raw urine: a reddish color appears, which vanishes on addition of acid. If the earthy phosphates appear a dirty gray, usually uroërythrine (p. 126), the coloring matter of febrile urine is present. To confirm this there must be present a rose-red sedimentum lateritium, or, upon addition of a few drops of acetate-of-lead solution, a reddish or flesh-colored precipitate should fall. If the earthy phosphates appear brown, usually the biliary coloring matters are present. If the biliary coloring matters are not decomposed, a beautiful iridescence may be obtained by Heller's test (p. 132). If no coloration occurs, and also no green color is obtained (Ultzmann's test), then decomposed biliary matters are present in the urine. By a relatively low specific gravity of the urine the H2SO, test is strengthened, and a mixture of the urine with potassium hydrate (KOH) appears more darkly colored. C. Test for the Normal Coloring Matters of the Urine. 1. Test with concentrated H2SO4 (p. 67, Heller's urophæine test). 2. Test for indican with concentrated HCl and bleaching-powder solution. (See p. 68.) D. Test for the Normal Inorganic Salts of the Urine. 1. For chlorides: Take the wine-glass which has been used for the HNO, test A, and, if much albumen has not separated, stir up the mixture of urine and HNO, with a glass rod and add one or two drops of a solution of nitrate of silver (AgNO3). (P. 73.) 2. For alkaline phosphates, with the magnesium fluid mixture (p. 80), after precipitating the earthy phosphates with KOH or NH4OH. 3. For sulphates, with barium chloride (p. 82). E. Further Tests for Abnormal Matters. If it is necessary to test for the more obscure substances which may be present, we use the aforementioned tests for ammonium carbonate (p. 142), hydrogen sulphide (p. 143), sodium carbonate (p. 144), and for leucine and tyrosine (p. 124). When the first three bodies are present, the urine is almost always alkaline. With the latter two, biliary matters are generally present. F. Investigation of the Sediment. The color and consistence of the sediment should first be observed (whether crystalline, pulverulent, flocculent, etc.), and also what is its chief constituent. We may do this either chemically or better microchemically and microscopically. ("Sediment," pages 146-189.) Finally, we determine the visible organized constituents of the sediment (epithelium, cylinders, spermatozoa, etc.) by means of the microscope. If the urine has been investigated in accordance with this scheme, it is convenient, for the beginner especially, to write in a concise form all that he has found, in order that he may draw his conclusions from a glance at the analysis. This form may be conveniently made by simply folding a sheet of paper three times (see p. 229). The abbreviations are as follows: H2 SO, test = Sulphuric-acid test for coloring matters. +Ur -Ur = = Urea. = Uric acid. = Chlorides. Cl E.ph. A. ph. Sul. In order to express whether the constituents are present in normal, increased, or diminished quantity, we employ the following: A normal amount present is denoted by n; a mod erate increase by m+; a moderate decrease by m —; |