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

  • Stirling, William, 1851-1932.
Date:
1902
Catalogue details

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.

    51/690 (page 21)
    [The furfurol reaction is often used not only for testing for the presence of carbohydrates, but also for that of carbohydrate groups in proteid bodies. Besides the Molisch-Udransky test above described, resorcin with HC1 (Seliwanoff), phloroglucin with HC1 (Tollens), and orcein (Tollens) have been used. On heating a sugar solution containing 18 p.c. HC1 with orcein, the solution becomes first red, then violet, and lastly bluish-green, and then blue-green flakes are deposited. This is used as a test for pen¬ toses. (Neuberg, Zeits. f. phys. Chem., xxxi., 564).] C. The Osazone reactions are of prime importance. Phenyl-hydrazine test.—(a) Two parts of phenyl-hydrazine hydrochloride and three of acetate of soda are mixed in a test- tube with 6 to 10 c.c. of dextrose solution. Boil in a water-bath for 30 minutes, and then place the tube in cold water or dextrose. A yellow crystalline deposit is formed, which, microscopically, consists of bright sulphur-colour yellow needles either detached or arranged in rosettes or feathery groups (fig. 3). The sub¬ stance formed is phenyl-glucosazone (C18H22N404), with a melting-point of 204° C. The arrangement of the acicular crystals I find frequently varies. Sometimes they are in rosettes (see “Urine”), and at other times more feathery. They are soluble in alcohol, and may be recrystallised from it. The phenyl-hydrazine test with sugars is a most impor¬ tant and reliable reaction for their identification. It forms with most sugars—when suffi¬ ciently heated—osazones, the several sugars yielding corre¬ sponding yellow osazones, which differ in solubility, crystalline form, and melting point (see “Appendix”). It is usually stated that the best proportions are 1 dextrose, 2 hydrochloride of phenyl- hydrazine, 3 sodium acetate, and 20 water. The substance formed is but slightly soluble in water. According to E. action which takes place :— ^6^-12^6 + 2C6H5N2H3 = 01sH22N404 + 2H20 + 2H. Phenyl -glucosazone. Fig. 3.—Crystals of Phenyl-Glucosazone, x 120. Fischer, the following is the re-