Elements of human physiology / by Henry Power.

  • Henry Power
Date:
1885
Catalogue details

Licence: Public Domain Mark

Credit: Elements of human physiology / by Henry Power. Source: Wellcome Collection.

    33/536 page 11
    Chap. I.] Carbohydra TES, 3. Tletrowshi's test.—Warm the liquid containing albumin with a moderate quantity of solution of potash or soda, and then add one or two drops of copper sulphate; the liquid assumes a violet colour. 4. Xanthoproteic reaction. — Heat with concentrated nitric acid; the liquid, if it contain a proteid, will assume a yellow tint, which becomes reddish-orange by the action of alkalies. 5. Millons test.—Millon's reagent is made by dissolving in the cold one part of mercury in its weight of concentrated nitric acid; the solution is completed by applying gentle warmth. Two volumes of distilled water are then added, and the fluid decanted. This test gives a red colour with liquids containing proteids, which is more marked when they are heated to 60° C. or 70° 0. 6. Adamkiewicz's test.—Every proteid, when dissolved in an excess of glacial acetic acid, gives, on the addition of con- centrated sulphuric acid, a beautiful violet colour and a slight fluorescence (Beaunis). Carbohydrates, These include: 1. Starch CgEioO,, formed in and produced by plants growing under the influence of light. It is often stored up as aliment in tubers and fruit, and consists of granules presenting concentric markings. It is insoluble in cold, but swells and becomes gelatinous in hot water, which dissolves the granulose, but leaves undissolved the cellulose of the starch granules. Gives a blue colour with free iodine. Exposed to heat the blue tint vanishes, but will return if the liquid be suddenly cooled. Starch, on being heated to 210° C, is converted into dextrin, which also appears in germinating seeds. When starch paste is boiled with dilute acid it is converted through some inter- mediate stages into dextrin and then into sugar, and the same conversion is effected by the saliva, pancreatic and intestinal juices. 2. Sugars.—These are substances having a more or less sweet taste, usually soluble in water, and destroyed by strong sul- phuric acid, which abstracts the water of these compounds and leaves only the carbon. The most important are glycose CgHi206, lactose C12H24O12, saccharose Ci2H220ii, and glyco- gen CgHjoOg. On fermentation they yield CO2 and alcohol. The tests for glycose are : 1. Trom7ner^s test, which depends on the circum- stance that sugar in an alkaline solution acts as a reducing agent. To the saccharine fluid about one-fourth of its bulk of soda or potash lye is added, and a dilute solution of cojoper sulphate.
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