TRITICUM HYBERNUM. ORD. LI. Gramina. 108 
wheat-flour, and on a due admixture of it with the constituents, depends 
the superiority of wheat-flour for making bread. 
Bread is made by working the flour into a paste with warm water, a 
quantity of ferment, such as yeast, and a little muriate of soda to render it 
sapid, allowing the paste to stand until a certain degree of fermentation 
takes place, and then baking it in an oven, heated to about 488°. During the 
fermentation, a quantity of gas is formed, and as it is prevented from escap- 
ing by the toughness of the paste, and dilated by the heat of the oven, the 
bread is rendered light and spongy. In this process, the nature of the con- 
stituents of the flour is altered; for we are not able to obtain either gluten 
or starch from bread. Water, in which flour has been macerated, acquires 
a sweetish taste and an opaline colour, and affords precipitates with infusion 
af galls and the strong acids. According to Vogel, 100 parts of flour con- 
_ tain—gluten, 24; saccharine-gum, 5; fecula, 68; albumen, 1,50. 
-Starch* is a fine white powder, generally concreted in friable hexagonal 
columns, smooth to the feel, and emitting a peculiar sound when compressed. 
It has neither taste nor odour, is decomposed by heat, is not soluble in cold 
water or in aleohol. Warm water, at about 190° Fah. converts itinto a kind 
of mucilage, which, on cooling, assumes a gelatinous consistence. This 
jelly, when dried by heat, becomes brittle and transparent like gum, but is 
not soluble in cold water. At 78° Fah. its watery solution ferments with the 
addition of yeast. By roasting, it becomes soluble in cold water, and it is 
converted by three or four hours boiling with sulphuric acid, into a saccha- 
rine liquid. Alcohol precipitates starch white and tough from its solutions; 
acetate of lead and infusion of galls also throw it down, but the precipitate 
formed by the latter is redissolved by heating the liquid to 120°. Both 
acids and alkalies combined with water, dissolve it. The strong acids de- 
compose it, especially the sulphuric and nitric acids; the latter converting 
it into malic and oxalic acids. When exposed to a moderate heat, it begins 
to swell, and is gradually chenged into a brownish substance, which is used 
* Searels is found in many vegetables, combined with different substances: — 1. with 
gluten or fibrin, as in wheat, rye, and other similar seeds; 2. with extractive, asin beans, 
peas, lupins, &c.; 3. with mucilaginous matter, as in unripe corn, the potatoe, and in 
many other roots ; 4. with saccharine matter, in beet-root, and in corn, after it has begun 
to germinate ; 5. with an acid principle, as in the root of the Burdock, Jatropha Mani- 
hot, Arum, i other tuberous roots. 
