Starch or Amylum, is a preparation from wheat, obtained by steeping the flour of that grain in cold water, then straining it through a cloth, and suffering the farinaceous particles to subside. In many places, however, it is manufactured in the following manner;
Pure wheat is put into tubs of water, and exposed to the heat of the sun, to induce a proper degree of fermentation; the water being changed twice every day, for six Or eight clays, according to the warmth of the season. When properly softened and fermented, it is poured into canvas bags, which are worked or beaten on a board, placed over an empty vessel, in order to extract the mealy part. When such vessel is filled with the liquid flour, a reddish fluid appears on the surface, which must be carefully skimmed, and pure water added ; when the whole ought to be briskly agitated, and allowed to subside. As the sediment increases, the water is gradually drained, and at length the starch is formed into cakes, which are cut in small pieces, and dried for use.
Good starch, when dry, is pulverulent, tasteless, without odour, insoluble both in cold water and ardent spirit: on the addition of boiling water, however, it forms Paste, or Pastry', of which the reader will find an account. - It is one of the constituent parts in all mealy or farinaceous seeds, fruits, roots, etc. of plants; though some vegetables contain a much larger proportion of it than others. Thus, the Wake-Robin, and White Bryony, afford more starch than potatoes; and the Salep-roots, especially those of the Meadow-OR-Chis, for the greatest part, consist of that valuable substance.
Starch being the basis of hair-powder, and also of extensive utility for domestic purposes, various experiments have been instituted, with a view to ascertain such vegetables as might be advantageously substituted for wheat. - As the der will find a recapitulation of those useful plants which have been mentioned throughout this work, in the General Index of Reference, we shall, at present, only notice the method adopted by Mrs. Gibbs, for preparing starch from the roots of the Wake-Robin ; for which the. Soceity for the Encouragement of Arts, etc. in 1797, presented her with their gold medal. She observes, in her communication, that such roots are found in the Isle of Portland, in the common fields, whence they may be dug out, cleansed, and pounded in a stone mortar with water. The whole is then strained, and the starch settles at bottom : a peck of these roots produced, upon an average, about four pounds of starch, which was sold at lid. per pound. - See also Wake-RobiN.
Starch pays, on importation, 5l 15s. 2 1/2d. per cwt.; and is prohibited to be imported in packages of less than 22-lbs. net weight.