VEGETABLE PRODUCTS. 



139 



taken out, pounded, and mixed with cold water. 

 After a few hours the starch collects as a sedi- 

 ment at tlie bottom of the vessel, and the fluid 

 above is poured off. This is the sago of the 

 shops. The roots of the orchis tribe afford a 

 starch called id/opand cassava; it is prepared from 

 the root of the poisonous Jatropha manchot, a 

 native of America. The husks of oats also, 

 treated by maceration in water, aiTord a starch 

 which in Scotland is used as an article of food 

 called sowins. Parmentier enumerates a list 

 of plants, from the roots of which starch may 

 be made, among which are the following : 



Arctium lappa 

 Atropa belladonna 

 Colchiciini antumnale 

 Spirtea filipendula 

 Ranunculus bulbosus 

 Scroplmlaria nodosa 

 Sambucus caeruleus 



• niger 



Orchis moria 

 mascula 



Imperatoria ostruthium 

 Kyosciamus niger 

 Rumex obtusifolius 



■ acutus 



• aquaticus 



Arum maculatuni 

 Iris pseudaeoms 

 ~ — foetidissima 

 Orobus tuberosns 

 Bunium bulbocastaneum 



Starch is also found in the following seeds : 



Wheat 



Barley 



Oats 



Rice 



Maise 



Millet seed 



Chestnut 



Horse-chestnut 



Peas 



Beans 



Acorns 



Various other substances somewhat similar to 

 starch have been discovered by chemists, such 

 as hordein from barley, and liclinein from Iceland 

 moss. Starch is one of the ingredients of all 

 food derived from vegetable grains, grasses, &c.; 

 and forms a nutritive diet both for man and many 

 animals. The latter feed upon it in that state 

 in which nature presents it; but man prepares 

 and cooks it so as to render it pleasing to his 

 taste, and more easily assimilated into his sys- 

 tem. In the arts starch is used to a considerable 

 extent, in stiffening linen goods, and preparing 

 them for taking on or rejecting particular dyes. 

 Wafers are also made of paste, and many trinkets 

 and ornaments. 



Gluten. That portion of the flower of wheat 

 wliicli remains insoluble after the application of 

 water in making starch, is called gluten. It is of a 

 dull, white, or brown colour, tough, elastic, taste- 

 less but possessed of a peculiar faint smell. It is 

 soluble in the acids and alkalis; but insoluble in 

 water and alcohol. When exposed to the at- 

 mosphere it becomes hard and tough, assumes a 

 dark brown colour, with a slight degree of trans- 

 parency, resembling animal glue; but it is brittle, 

 and breaks like a piece of glass. When kept in 

 a damp situation it undergoes a kind of fermen- 

 tation, in which it swells and emits air bubbles, 

 consisting of hydrogen and carbonic acid gas. 

 When exposed in a dry state to heat, it cracks. 



swells, and melts, and exhales a fetid odour, burn- 

 ing like horns or feathei's. When distilled it 

 yields ammonia and an empyreumatic oil, and 

 leaves a charcoal that is with difficulty reduced 

 to ashes. Gluten, then, in many of its charac- 

 teristics, resembles closely animal jelly, particu- 

 larly in its fermentation and destructive distilla- 

 tion, and in its containing a portion of nitrogen. 

 Gluten is found in a great proportion of vege- 

 table substances, as well as in wheat. RoweUe 

 found it existing in the green fecula of plants; 

 and 'Proust detected it in peas, beans, barley, 

 rye, acorns, chestnuts, horse-chestnuts, apples, 

 quinces, elder-berries, gi-apes ; in the leaves 

 of rue, cabbage, cresses, hemlock, borage, saffron, 

 and in the petals of the rose. As regards the 

 food of man it seems one of the most important 

 of vegetable products, especially in the forma- 

 tion of wheaten bread, the great staple of life. 

 It is also used in fonning cements, and as a 

 ground for varnishing. Gluten has been resolved 

 by chemists into four distinct principles : alhu- 

 jnen, emulsion, mucin, and gluten. 



Albumen. Animal albumen is a glairy, taste- 

 less fluid, exemplified in the white of an egg. 

 Its existence, in vegetables, was first announced 

 by Fourcroy, and afterwards confirmed by Vau- 

 quelin, who pointed it out on the dried juice of 

 the papan tree, a plant indigenous to India and 

 the isle of France. A specimen of this juice, 

 which often exudes from the tree, in a viscid 

 and milky state, was brought to Paris by Char- 

 parbier after being evaporated to dryness, and 

 presented to Vauquelin. It was somewhat yel- 

 lowish and semi-transparent, and its taste wa." 

 sweetish; but it had no smell. When it was 

 subjected to maceration in cold water, the greater 

 part of it was dissolved. The solution frothed 

 with soap, and was coagulated, and rendered 

 white by the addition of nitric acid. When 

 boiled it precipitated white flakes, which were 

 coagulated albumen, possessing all the properties 

 by which it is distinguished in animals; disen- 

 gaging ammonia, by burning and yielding at the 

 same time carbonic acid and water. And hence 

 its relation to animal gluten is -established, and 

 the elements of its composition ascertained, whicli 

 are as follows: 



Carbon 

 Oxygen . 

 Hydrogen . 



Nitrogen 



S2.883 



. 23.87-2 



7..540 



16.705 



Albumen has not been found in such abundance 

 in any other plant as in that just alluded to. 

 But it has been asceilained to exist in mush- 

 rooms, and some other of the fungi; and the 

 juice of the fruit of hibiscus esciilentits, a West 

 Indian plant, is said to contain such a propor- 

 tion of it as to render it fit to be employed as a 

 substitute for the white of eggs in clarifying 



