Manuals of food : food / Albert J. Bernays.

  • Bernays, Albert James, 1823-1892
Date:
[1876?]
Catalogue details

Licence: Public Domain Mark

Credit: Manuals of food : food / Albert J. Bernays. Source: Wellcome Collection.

    31/140 (page 25)
    [Cellulose, CigHgoOu, is evidently produced from stai'ch, and, like the latter, is a compound of carbon and the elements of water. When burnt in oxygen, it is changed into carbonic acid and water.] 30. Yet another principle, which, like starch and cellulose, extensively pervades the vegetable kingdom, is the substance which gives to many fruits and vege- tables the power of forming a jelly. It is known to chemists by the name of pectin, and contains, in some- what different proportions, the same elements—cai’bon hydrogen, and oxygen. 31. Pectin must not be confounded with gum, which is found in the juices of almost all plants, but is met with in its purest form in gum-arabic ; nor must gum, or arabin, as it is called, be mistaken for mucilage, which is insoluble in water. Many seeds furnish mucilage largely; such as linseed, quince-seed; and roots, such as the marsh-mallow: when moistened Avith water, mucilage swells up into a gelatinous mass. In chemical composition, mucilage is identical with stai’ch, and arabin with cane-sugar. Both of them consist of carbon and the elements of water. 32. Whether then we speak of starch or dextrin, of CELLULOSE or PECTIN, of ARABIN or MUCILAGE, they all belong to that class of foods known as carbonaceous. They consist only of carbon, hydrogen, and oxygen. CHAPTEB III. THE SUGARS. 33. The sugars are so closely related to the starches, and so nearly resemble them in chemical