Outlines of practical physiology : being a manual for the physiological laboratory, including chemical and experimental physiology, with reference to practical medicine / by William Stirling.

  • William Stirling
Date:
1902
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Licence: Public Domain Mark

Credit: Outlines of practical physiology : being a manual for the physiological laboratory, including chemical and experimental physiology, with reference to practical medicine / by William Stirling. Source: Wellcome Collection.

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    teids—exist in combination with nuclein in fish sperm. They yield bases containing 6 atoms of carbon, and these bases as a group have been called hexones—e.g., lysin, arginin, histidin.] Additional Exercises. 1. Reaction of Adamkiewicz.—To white of egg add glacial acetic acid, and heat to get it in solution ; gradually add concentrated H2S04 = a violet colour with slight fluorescence (not given by gelatine). (Impurity in A acid—Hopkins, Proc. R. 8., 1901.) 2. Liebermann’s reaction. —Wash finely powdered albumin with alcohol and then with cold ether, and heat the washed residue with con¬ centrated HC1 acid = a deep violet-blue colour. This is best done in a white porcelain capsule, or on a filter-paper in a funnel; in the latter case the boiling acid is poured gently down the side of the filter-paper ; or to 3 c.c. HC1 + 2 drops undiluted egg-white. Boil = pink or violet colour. Avoid excess of water. Colour reactions with cobalt (see Pickering, Journ. of Phys., xiv., 1893). The proteid molecule contains several aromatic groups :—(1) Oxy- phenol group, represented by phenol and tyrosin. The xanthoproteic and Millon’s reactions are due to the formation of nitro-products from this group. (2) Phenyl group, by phenyl-acetic acid. (3) The indol group, by indol and skatol. The Adamkiewicz reaction is due to this group (Novy). Liebermann’s reaction does not appear to be due to the aromatic group. 3. Indiffusibiiity of egg-albumm (and most proteids).—Place egg- white solution in a dialyser or parchment-paper sausage-tube. Suspend in a tall glass jar (Lesson IX.) of distilled water. The salts (crystalloids) diffuse readily (test for chlorides by AgN03 and HNO3). Test the diffusate for proteids = result negative. (Peptones diffuse through animal membranes.) 4. Nitrogen and sulphur in albumin. — (a) Place powdered dried albumin in a reduction tube, and into the mouth of the tube insert (1) a red litmus paper, and (2) a lead acetate paper. On heating the tube, the former becomes blue from the escape of ammonia, which can also be smelt (odour of burned feathers), and the latter black from the formation of lead sulphide (b) Heat dry proteid with excess of soda-lime in a hard dry tube or spoon. It is charred, and ammonia vapour is evolved. The charring shows the presence of C and the ammonia the presence of N. (c) Heat in a dry hard tube—at first slowly, and then strongly—dry proteid with a small piece of metallic sodium, cool, add 3 c. c. water to the NaCy residue, filter, and to the filtrate add a few drops of ferric chloride and ferrous sulphate, and then excess of HC1. If nitrogen be present, there is a precipitate of Berlin blue, sometimes only seen after standing for a time. (d) To a solution of albumin add an equal volume of solution of caustic potash and a few drops of lead acetate and boil for some time = slowly a brownish colouration, due to lead sulphide. 5. Temperature of coagulation (fig. 1).—The reaction of the fluid must be neutral or feebly acid. “A glass beaker containing water is placed within a second larger beaker also containing water, the two bein- sepa¬ rated by a ring of cork. Into the water contained in the inner beaker there is immersed a test-tube, in which is fixed an accurately graduated