Chemistry of urine : a practical guide to the analytical examination of diabetic albuminous, and gouty urine / Alfred H. Allen.

  • Alfred Henry Allen
Date:
1895
Catalogue details

Licence: Public Domain Mark

Credit: Chemistry of urine : a practical guide to the analytical examination of diabetic albuminous, and gouty urine / Alfred H. Allen. Source: Wellcome Collection.

    50/250 (page 32)
    on oxidation with nitric acid, and. Iscvulic acid by treatment with hydrochloric acid. It does not ferment with yeast, is precipitated by alcohol, and gives no coloration with iodine. Glycogen, (CgHjoOg)^, has been termed “ animal starch,” and presents the closest analogy to soluble starch. It was first found in the liver, but has more recently been met with in many other parts of the body. Pure glycogen is a white, amorphous powder, readily soluble in water to form a solution which is usually, but not invariably, opalescent, and becomes more limpid on adding acetic acid or an alkali. Glycogen is precipitated from its aqueous solution by alcohol whenever the alcohol amounts to 60 per cent, of the liquid. If the solution be quite free from salts, the separation is sometimes very difficult, but takes place instantly on adding a minute quantity of com- mon salt. The precipitation of glycogen in liquids containing 60 per cent, of alcohol distinguishes it from the different varieties of dextrin, none of which are precipitated by alcohol of less than 85 per cent, strength. Glycogen exactly simulates dextrin in its behaviour with a solution of iodine, which produces a port-wine colour, disappearing on heating, and return- ing as the liquid cools. Glycogen is strongly dextro-rotatory, the value of [a]i) varying from + 203° to -H 234°, according to the concentration of the solution. Glycogen does not reduce Fehling’s solution. It is precipitated by baryta-water as BaO(C6HioOe)3, and by basic lead acetate as PbO(C6HioOg)2. When boiled with dilute nitric acid, gl}^cogen yields oxalic acid. Boiled with dilute sulphuric or hydro- chloric acid, it is converted into dextrose. It does not ferment with yeast, but diastase and saliva convert it