Volume 1

A text-book of human physiology : including histology and microscopical anatomy with special reference to the requirements of practical medicine / by L. Landois ; translated from the seventh German edition with additions by William Stirling.

  • Landois, L. (Leonard), 1837-1902. Lehrbuch der Physiologie des Menschen. English
Date:
1891
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Licence: Public Domain Mark

Credit: A text-book of human physiology : including histology and microscopical anatomy with special reference to the requirements of practical medicine / by L. Landois ; translated from the seventh German edition with additions by William Stirling. Source: Wellcome Collection.

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    with the ferrocyanide test for albumin. He finds that minute traces of proteid are detected by the following modification of the biuret test:—Make the urine alkaline, and by the contact method bring a layer of very dilute cupric sulphate over it; when the two fluids touch, a reddish-violet ring is obtained.] The tests for albumin in urine depend upon the facts that it is coagulated by heat in neutral or acid solutions, and it is precipitated by various reagents. [(1) Heller's Test.—Place 10 c.c. of the urine in a test-glass, and pour in pure colourless HNO3 so as to run down the side of the glass, forming a layer beneath the urine. A white zone of coagulated albumin indicates the presence of albumin. In this test it is important to wait a certain time for the development of the reaction. In urines of high specific gravity, a haziness due to acid urates may be formed above where the two fluids meet, but its upper edge is not circumscribed. The acid decomposes the neutral urates and forms a more insoluble acid salt. This cloud of acid urates is readily dissolved by heat, while the albumin is not; the latter is always a sharply defined zone between the two fluids. In very concentrated urine (rare), nitric acid may gradually precipitate crystalline urea nitrate. In patients taking copaiba, nitric acid, by acting on the resin, causes a slight milkiness.] [(2) Boiling and Ni'tric Acid.—Place 10 c.c. of urine in a test-tube and boil. If albumin be present in small quantity, a faint haziness, which may be detected in a proper light, will be produced. Add 10 to 12 drops of HNO3. If the turbidity disappears it is due to phosphates, while if any remains it is due to albumin. If albumin be present in large quantity, a copious whitish coagulum is'obtained. Precautions.—{a) In all cases, if the urine be turbid, filter it before applying any test, {b) How to boil.—Boil the upper strata of the liquid, and take care, if any coagulum be formed, that it does not adhere to the side of the tube, else the tube is liable to break, (c) In performing this test with a neutral solution, note when the precipitate falls, for albumin is precipitated about 70° C, phosphates not till about the boiling point, {cl) Amount of Acid.—If too little (2 or 3 drops) HNO3 be added, or too much (30 or 40 drops), we may fail to detect albumin, although it is present.] (3) Ferrocyanide Test.—By the addition of acetic acid and potassium ferrocyanide. [If albumin be present, a white flocculent precipitate separates in the cold. Dr Pavy has intro- duced pellets, consisting of a mixture of citric acid and sodic ferrocyanide. All that is required is to add a pellet to the suspected urine. Oliver's Papers.—Dr Oliver uses papers, one saturated with citric acid and another with ferrocyanide of potassium. The two papers are added to the clear filtered urine. Other precipitants of albumin, such as small pieces of paper impregnated Avith potassio-mercuric iodide, are used by Oliver.] (4) Boiling Acid Urine.—If the urine be alkaline, although albumin may be present, it is not precipitated by heat alone. We require to add acetic acid until a slightly acid reaction is obtained. Boiling may give a precipitate of earthy phosphates in an alkaline urine, owing perhaps to the COo being driven oft. This precipitate might be mistaken for albumin, but on adding acetic acid or nitric acid, the earthy precipitate is dissolved, while the precipitate of albumin is not dissolved. In testing for albumin, always use clear urine. If it is turbid, filter it. [(5) Metaphosphoric acid is dissolved in water just before it is to be used and added to clear urine {Hindcnlang). Graham pointed out that metaphosphoric acid precipitated albumin. A 20 per cent, solution of the ordinary glacial phosphoric acid is a good test for albumin, but it also ]n-ecipitates peptones. It, however, changes into ordinary phosphoric acid by keeping, and then it no longer precipitates albumin.] [(6) Sodic Sulphate and Acetic Acid.—Acidulate 10 c.c.of urine with acetic acid, and add I of its volume of a concentrated solution of sulphate of soda or magnesia. On heating, if albumin be present, a distinct cloudiness is obtained.] [(7) In picric acid according to Dr Johnson, we have a more delicate test for minute traces of albumin than either heat or nitric acid, or than both these tests combined. It is used either in the form of crystals or powder, or as a saturated aqueous solution. Take a four-inch column of urine in a test-tube, hold the tube in a slanting direction, and pour an inch of the picric acid solution on the surface of the urine, where, in consequence of its low specific gravity (1005), it mixes only with the upper layer of the urine. It coagulates any albumin present. The precipitate occurs at once, and is increased by heat, while the urate of soda, which is sometimes precipitated, is soluble on heating. Peptones and albumoses are also precipitated by this reagent, but the precipitate redissolves on heating.] [(8) Potassio-mercuric iodide, or Tanret's reagent, gives a white precipitate. This is a very delicate test, but it also precipitates peptones and albumoses (but these precipitates are dissolved by heat), alkaloids, and bile-salts. The reagent consists of mercuric chloride, 1'35 grams ; potassium iodide, 3'32 grams ; acetic acid, 20 c.c. ; and water, 64 c.c] [Dr Roberts regards any test for albumin which requires strong acidulation with an organic acid, citric, acetic, or lactic, as unsatisfactory, since it precipitates mucin. For this reason he rejects the tungstate, mercuric iodide, and potassic ferrocyanide tests. Dr Roberts regards the
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