142 VEGETABLE PRODUCTS. GUM. 



consider this to be the substance contained in the interior of the 

 starch grains. When dried, it constitutes British gum. It is one 

 of the steps in the process of the conversion of starch into sugar. 



303. Gum is one of the substances which are produced abundantly 

 in the vegetable kingdom. Its composition is C 12 H u O 11 , the same 

 as that of Cane-sugar. It exists in many seeds, exudes from the 

 stems and twigs of many trees, and is contained in the juices of others 

 from which it does not exude. It is one of the forms through which 

 organic matter passes during the growth of plants. The different 

 kinds of gums have been divided into those which are soluble in cold 

 water (Arabine, mucilage), and those which only swell up into a gela- 

 tinous matter (Bassorine or Tragacanth, Cerasine and Pectine). Ara- 

 bine is familiarly known by the name of gum-arabic or gum-senegal, 

 and is the produce of various species of Acacia, chiefly natives of Arabia, 

 Egypt, Nubia, and Senegambia, such as Acacia Ehrenbergii, tortilis, 

 Seyal, arabica, vera, and albida. From the bark of these plants it 

 exudes in the form of a thick juice, which afterwards concretes into 

 tears. Old stunted trees, in hot and dry seasons, yield the most gum. 

 Arabine exists with cerasine in the gum of the Cherry and Plum. 

 Mucilage is present in many of the Mallow tribe, as Malva sylvestris, 

 Althaea officinalis or marsh mallow, and in Linseed. In Sphserococcus 

 crispus, mucilage is present, of which the formula is C 24 H 19 O 19 . 

 Bassorine forms the chief part of gum-tragacanth, the produce of several 

 species of Astragalus, and of gum-bassora. It exists in Salep, procured 

 from the tubercules of Orchis mascula. Cerasine is that part of the 

 gum of the Cherry (Cerosws), Plum, and Almond trees, which is 

 insoluble in cold water. Pectine is a substance procured from pulpy 

 fruits, as the apple and pear. It forms a jelly with water, and when 

 dried, resembles gum or isinglass. It is changed by alkalies into 

 pectic acid, which is found in many fruits and esculent roots. 



304. Sugar. This substance which forms an important article of 

 diet, exists in many species of plants. Sugars have been divided into 

 those which undergo vinous fermentation, as Cane and Grape sugar, 

 and those which are not fermentescible as Mannite. Cane sugar, C 12 H 9 

 O 9 -\- 2 HO, is procured from Saccharum officinarum (sugar-cane), 

 Beta vulgaris (beet-root), Acer saccharinum (sugar-maple), and many 

 other plants. It has been conjectured that the Calamus or sweet 

 cane mentioned in the Old Testament, may be the sugar cane. At 

 all events, the plant was known as early as the commencement of the 

 Christian era. In the East and West Indies, at the present time, 

 numerous varieties of cane are cultivated, such as Country cane, Ribbon 

 cane, Bourbon cane, Violet or Batavian cane, which are distinguished 

 by their size, form, the position and colour of their joints, their 

 foliage, and their glumes. Bourbon cane is richest in saccharine 

 matter. Canes demand a fertile soil, and for their perfect maturation 



