LACTOSE. C12H24012 INOSITE. C6H12O6 THESE substances are also termed Carbo-hydrates, from the fact of their containing Hydrogen and Oxygen in proportion to form water, united with Carbon. Owing to this composition they are readily converted the one into the other by the removal or addition of the elements of water; thus, CH10O5+ H2O = C6H12O6 The carbo-hydrates closely resemble one another in their chemical characters. They are neutral in their B reaction, and have little disposition to enter into They all have a strong action on combination. polarized light. The saccharine principles (with the exception of inosite) reduce alkaline copper solutions, throwing down the cuprous oxide. Boiled with liquor potassæ, they give a brown colour to the solution. And their solutions undergo vinous fermentation when yeast is added. The amylaceous principles are converted into the saccharine by the action of dilute acids, and by the salivary, pancreatic, and intestinal juices; treated with free iodine they form coloured compounds, that of starch yielding a characteristic deep blue colour, and glycogen a violet or maroon red coloration. (1) STARCH. C6H1005. Starch is one of the chief constituents of our food, but being very insoluble it is converted into grape sugar by the action of the salivary, pancreatic, and intestinal juices to allow of its absorption from the intestinal canal. In certain parts of the body, as in the prostate, in the ependyma of the ventricles, the fornix, the choroid plexus, the retina, and spinal cord, starch granules, the "corpora amylacea" of Kolliker and Purkinje, are sometimes found in advanced age. Chemical and physical characters occur in small rounded granules of irregular form, marked with concentric laminæ, and having a pore, "the hilum," at one spot on its surface. Starch is insoluble in cold water, but on being boiled it swells up, the granules burst and form a stiff paste. REACTIONS.—Make a solution of starch by adding an extremely small quantity of starch (1 part of starch to 25 |