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Is a substance which is extracted from wheaten flour, by washing it in water. All farinaceous seeds, and the roots of most vegetables, afford this substance in a greater or less degree; but it is most easily obtained from the flour of wheat, by moistening any quantity thereof 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 of a long figure and columnar shape, 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.

It is not soluble in cold water; but forms a thick paste with boiling-hot water, and when this paste is allowed to cool, it becomes semi-transparent and gelatinous, and being dried, becomes brittle, and somewhat resembles gum. Starch, although found in all nutritive grains, is only perfect when they have attained maturity, for before this it is in a state approaching to mucilage, and so mixed with saccharine matter and essential oils, that it cannot be extracted in sufficient purity to concrete into masses. Wheat, or such parts of it as are not used for human food, are usually employed for manufacturing starch, such as the refuse wheat and bran; but when the finest starch is required, good grain must be used. This, being 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 canvas 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 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 extract any more starch, or become colored by the grain. The water in the settling-vessels being left at rest, precipitates the starch which it 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. During this process, the starch for sale in the shops receives its colour, which consists of smalt mixed with water and a small quantity of alum, and is thoroughly incorporated with the starch; but this starch is unfit for medicinal purposes. 

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 or 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 by 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 dried starch are scraped, to remove the outside crust, which makes inferior starch, and these pieces are broken into smaller pieces for sale. The grain which remains in the sack after the starch is extracted, contains the husks and the glutinous part of the wheat, which are found very nutritious food for cattle. The French manufacturers, according to "Les Arts et Metiers," pursue a more economical method, as they are enabled, by employing an acid water for the fermentation in the first instance, to use the most inferior wheat, and the bran or husks of wheat. This water they prepare, by putting a pailful of warm water into a tub, with about two pounds of leaven, such as some bakers use to make their dough rise or ferment. 

The water stands two days, and is then stirred up, and half a pailful of warm water added to it; then being left to settle till it is clear, it is poured off for use. To use this water in the fermentation of the materials, a quantity of it is poured into a tub, and about as much fair water is poured upon it as will fill the tub half full: the remainder of the tub is then filled up with the materials, which are one half refuse wheat, and the other half bran. In this tub it continues to steep and ferment during ten days, or less, according to the strength of the leaven-water, and according to the disposition of the weather for fermentation. When the materials have been sufficiently steeped, or fermented, an unctuous matter, which is the oil of the grain, will be seen swimming on the surface, having been thrown up by the fermentation. This must be scummed off; and the fermented grain, being taken out of the tub, is put into a fine hair sieve, placed over a settling-tub, when fair water is poured upon it, and washed through the sieve into the tub; by which means the starch is carried through the sieve with the water, of which about six times the quantity of the grain are used. The water stands in the settling tub for a day, and becomes clear at top; when it is carefully laded out of the tub, leaving at the bottom a white sediment, which is the starch. The water which is taken off is sour, and is called _sure_ water: this is the proper leaven for the first steeping of the materials. 

The starch now obtained must be rendered marketable; for which purpose, as much water is poured upon it as will enable it to be pounded and broken up with a shovel, and then the tub is filled up with fair water. Two days after this, the water is laded out from the tub, and the starch appears in the bottom, but covered over with a dark-colored and inferior kind of starch, which is taken off, and employed for fattening hogs. The remainder of the sediment, which is good starch, is washed several times, to remove all the inferior starch; and when this is done, about four inches of thick starch should be found at the bottom of each tub: but the quantity varies, according to the goodness of the meal or bran which has been used. It is evident that the refuse wheat, when employed for making starch, ought to afford more, the whole being used, than the bran or husks; but the starch so extracted is always of an inferior quality to that which is extracted from the bran of good wheat, particularly in the whiteness of its color. The starch in the different tubs is brought together into one, and there worked up with as much water as will dissolve it into a thin paste, which is put into a silk sieve, and strained through with fresh water. This water is settled in a tub, and afterwards poured off, but before it is so completely settled as to lose all its white color: this renders the starch which is deposited, still finer and whiter; and the starch which is deposited by the water so poured off, is of a more common quality. 

The starch, thus purified, is taken out of the bottom of the tubs, and put into wicker-baskets, about eighteen inches long and ten deep, rounded at the corners, and lined with linen cloths, which are not fastened to the baskets. The water drips from the starch through the cloths for a day, and the baskets are then carried up to apartments at the top of the house, where the floor is made of very clean white plaster; and the windows are thrown open, to admit a current of air. Here the baskets are turned downwards upon the plaster-floor, and the linen cloths, not being fastened to the baskets, follow the starch, and when taken off, leave loaves, or cakes of starch, which are left to dry a little, and are then broken into smaller pieces, and left on the plaster-floor, till very dry. But if the weather is at all humid, the starch is removed from the plaster-floor and spread out upon shelves, in an apartment which is warmed by a stove, and there it remains till perfectly dry. The pieces are afterwards scraped, to remove the outside crust, which makes common starch; and the scraped pieces being again broken small, the starch is carried to the stove, and spread out to a depth of three inches, on hurdles covered with cloths. The starch must be turned over every morning and evening, to prevent it from turning to a greenish colour, which it would otherwise do. Those manufacturers who are not provided with a stove, make use of the top of a baker's oven to spread the starch upon; and after being thoroughly dried here, it is ready for sale. 

Starch may be made from potatoes, by soaking them about an hour in water, and taking off their roots and fibres, then rubbing them quite clean by a strong brush: after this they are reduced to a pulp, by grating them in water. This pulp is to be collected in a tub, and mixed up with a large quantity of clear water: at the same time, another clean tub must be provided; and a hair sieve, not too fine, must be supported over it by two wooden rails extended across the tub. The pulp and water are thrown into the sieve, and the flour of starch is carried through with the water; fresh water must then be poured on, till it runs through quite clear. The refuse pulp which remains in the sieve, being boiled in water, makes an excellent food for animals; and the quantity of this pulp is near seven-eighths of all the potatoes employed. The liquor which has passed through the sieve is turbid, and of a darkish color, from the extractive matter which is dissolved in it. When it is suffered to rest for five or six hours, all this matter deposits or settles to the bottom, and the liquor which remains is to be poured off as useless; and a large quantity of fresh water is thrown upon the flour, and stirred up: it is then settled for a day, and the water being poured off, the flour will be found to have again settled in a whiter state. But to improve it, another quantity of water is poured on, and mixed up with it; in which state it is passed through a fine silk sieve, to arrest any small quantity of the pulp which may have escaped the first hair sieve. The whole must afterwards be suffered to stand quiet, till the flour is entirely settled, and the water above become perfectly clear; but if the water has any sensible color or taste, the flour must be washed again with fresh water, for it is absolutely necessary that none of the extractive matter be suffered to remain with it. 

The flour, when thus obtained pure, and drained from the water, may be taken out of the tub with a wooden shovel, and placed upon wicker-frames covered with paper, to be dried in some situation properly defended from dust. When the manufacture of starch from potatoes is attempted in a large way, some kind of mill must be used to reduce them to a pulp, as the grating of them by hand is too tedious an operation. A mill invented by M. Baumé is very complete for this purpose. In its general structure it resembles a large coffee-mill: the grater consists of a cone of iron plate, about seven inches in diameter, and eight inches in height, the exterior surface of which is made toothed, like a rasp, by piercing holes through the plate from the inside. This cone is fixed upon a vertical axle, with a handle at the top to turn it by; and is mounted on the pivots of the axle, within a hollow cylinder of plate-iron, toothed with inside like the outside of the cone; the smallest end of the interior cone being uppermost, and the lower or larger end being as large as the interior diameter of the hollow cylinder. 

A conical hopper is fixed to the hollow cylinder, round the top of it, into which the potatoes are thrown; and falling down into the space between the outside of the cone and the inside of the hollow cylinder, they are ground, and reduced to a pulp, when the interior cone is turned round by its handle; and as the lower part of the cone is fitted close to the interior diameter of the cylinder, the potatoes must be ground to a fine pulp before they can pass through between the two. The machine, when at work, is placed in a tub filled with water; and as fast as the grinding proceeds, the pulp mixes regularly with the water, ready for the process before described. Poland starch is reckoned the best: its quality may be judged of by the fineness of the grain, its being very brittle, and of a good color. The price of starch depends upon that of flour; and when bread is cheap, starch may be bought to advantage. If it be of good quality it will keep for some years, covered close, and laid up in a dry warm room. In the year 1796, lord William Murray obtained a patent for manufacturing starch from horse-chesnuts. 

The method was to take the horse-chestnuts out of the outward green prickly husk, and either by hand, with a knife or tool, or else with a mill adapted for the purpose, the brown rind was carefully removed, leaving the chestnuts perfectly white, and without the smallest speck. In this state the nuts were rasped or ground to a pulp with water, and the pulp washed with water through a coarse horse-hair sieve, and twice afterwards through finer sieves, with a constant addition of clear cold water, till all the starch was washed clean from the pulp which remained in the sieve; and the water being settled, deposited the starch, which was afterwards repeatedly washed, purified, and dried, in the same manner as the potato-starch before described. We are not informed if this manufacture has been carried into effect. 

The sour, nauseous, milky liquor obtained in the process of starch-making, appears, upon analysis, to contain acetous acid, ammonia, alcohol, gluten, and phosphate of lime. The office of the acid is to dissolve the gluten and phosphate of lime, and thus to separate them from the starch. Starch is used along with smalt, or stone-blue, to stiffen and clear linen. The powder of it is also used to whiten and powder the hair. It is also used by the dyers, to dispose their stuffs to take colours the better. Starch is sometimes used instead of sugar-candy for mixing with the colours that are used in strong gum-water, to make them work more freely, and to prevent their cracking. It is also used medicinally for the same intentions with the viscous substance which the flour of wheat forms with milk, in fluxes and catarrhs, under various forms of powders, mixtures, &c. A drachm of starch, with three ounces of any agreeable simple water, and a little sugar, compose an elegant jelly, of which a spoonful may be taken every hour or two. These gelatinous mixtures are likewise an useful injection in some diarrhoeas, particularly where the lower intestines have their natural mucus rubbed off by the flux, or are constantly irritated by the acrimony of the matter.