A well-known substance extracted from wheaten flour, by washing it in water. All farinaceous seeds afford this substance in a greater or less degree; but it is most easily obtained from the flour of wheat, by moistening any quantity with a little water, and kneading it with the hand into a tough paste; this being washed with water, by letting fall upon it a very slender stream, the water will be rendered turbid as it runs off,' in consequence of the fecula or starch which it extracts from the flour, and which will subside when the water is allowed to stand at rest. The starch so obtained, when dried in the sun, or by a stove, is usually concreted into small masses, which have a fine white colour, scarcely any smell, and very little taste. If kept dry, starch in this state continues a long time uninjured, although exposed to the air. The inferior and refuse wheat is usually employed for manufacturing common starch; but when the finest starch is required, good grain must be used. This, beinf well cleaned, and sometimes coarsely bruised, is put into wooden vessels full of water, to ferment: to assist the fermentation, the vessels are exposed to the greatest heat of the sun, and the water is changed twice a day, during eight or twelve days, according to the season.
When the grain bursts easily under the finger, and gives out a milky white liquor when squeezed, it is judged to be sufficiently softened and fermented. In this state the grains are taken out of the water by a sieve, and put into a canvass sack, and the husks are separated and rubbed off by beating and rubbing the sack upon a plank: the sack is then put into a tub filled with cold water, and trodden or beaten till the water becomes milky and turbid, from the starch which it takes up from the grain. A scum sometimes swims upon the surface of the water, which must be carefully removed; the water is then run off through a fine sieve into a settling vessel, and fresh water is poured upon the grains, two or three times, till it will not extrac, any more starch, or become coloured by the grain. The water in the settling vessels, being left at rest, precipitates the starch, which is held suspended; and to get rid of the saccharine matter, which was also dissolved by the water, the vessels are exposed to the sun, which soon produces the acetous fermentation, and takes up such matter as renders the starch more pure and white.
When the water becomes completely sour, it is poured gently off from the starch, which is washed several times afterwards with clean water, and at last is placed to drain upon linen cloths, supported by hurdles, and the water drips through, leaving the starch upon the cloths, in which it is pressed and wrung, to extract as much as possible of the water; and the remainder is evaporated by cutting the starch into pieces, which are laid up in airy places, upon a floor of plaster, or of slightly burnt bricks, until it becomes completely dried from all moisture, partly from the access of warm air, and partly by the floor imbibing the moisture. In winter time, the heat of a stove must be employed to effect the drying. Lastly, the pieces of starch are scraped to remove the outside crust, which makes inferior starch, and these pieces are broken into smaller pieces for sale.