Abbildungen der Seite
[ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

ABRAHAM REES, D.D. F. R. S. F. L. S. S. Amer. Soc.
















TARCH, a substance which is extracted from wheaten flour, by washing it in water. All farinaceous feeds, and the roots of moft vegetables, afford this fubftance in a greater or lefs degree; but it is molt eafily obtained from the flour of wheat, by moistening any quantity thereof with a little water, and kneading it with the hand into a tough pafte: this being washed with water, by letting fall upon it a very flender ftream, the water will be rendered turbid as it runs off, in confequence of the fecula or ftarch which it extracts from the flour, and which will fubfide when the water is allowed to ftand at reft. The refiduum of the flour, which remains after the water has extracted all the fecula, and runs off colourlefs, will be found to be gluten; which fee. The ftarch fo obtained, when dried in the fun, or by a ftove, is ufually concreted into small maffes of a long figure and columnar fhape, which have a fine white colour, fcarcely any fmell, and very little tafte. If kept dry, ftarch in this ftate continues a long time uninjured, although expofed to the air. It is not foluble in cold water; but forms a thick pate with boiling-hot water, and when this paste is allowed to cool, it becomes femitransparent and gelatinous, and being dried, becomes brittle, and fomewhat resembles gum. Starch, although found in all nutritive grains, is only perfect when they have attained maturity, for before this it is in a ftate approaching to mucilage, and fo mixed with faccharine matter and effential oils, that it cannot be extracted in fufficient purity to concrete into masses.

Wheat, or fuch parts of it as are not used for human food, are ufually employed for manufacturing ftarch, fuch as the refuse wheat and bran; but when the fineft ftarch is required, good grain must be used. This, being well cleaned, and fome times coarsely bruifed, is put into wooden veffels full of water to ferment; to affift the fermentation, the veffels are expofed to the greatest heat of the fun, and the water is changed twice VOL. XXXIV.

a day, during eight or twelve days, according to the feason. When the grain burfts easily under the finger, and gives out a milky white liquor when fqueezed, it is judged to be fufficiently foftened and fermented. In this ftate, the grains are taken out of the water by a fieve, and put into a canvas fack, and the hufks are feparated and rubbed off, by beating and rubbing the fack upon a plank: the fack is then put into a tub filled with cold water, and trodden or beaten till the water becomes milky and turbid, from the ftarch which it takes up from the grain. A fcum fometimes swims upon the furface of the water, which must be carefully removed; the water is then run off through a fine fieve into a fettling. veffel, and fresh water is poured upon the grains, two or three times, till it will not extract any more ftarch, or be come coloured by the grain. The water in the fettlingveffels being left at reft, precipitates the ftarch which it held fufpended; and to get rid of the faccharine matter, which was alfo diffolved by the water, the veffels are expofed to the fun, which foon produces the acetous fermentation, and takes up fuch matter as renders the ftarch more pure and white. During this procefs, the ftarch for fale in the shops receives its colour, which confifts of fmalt mixed with water and a fmall quantity of alum, and is thoroughly incorporated with the ftarch; but this ftarch is unfit for medicinal purposes. When the water becomes completely four, it is poured gently off from the ftarch, which is washed feveral times afterwards with clean water, and at laft is placed to drain upon linen cloths fupported by hurdles, and the water drips through, leaving the starch upon the cloths, in which it is preffed or wrung, to extract as much as poffible of the water; and the remainder is evaporated, by cutting the ftarch into pieces, which are laid up in airy places, upon a floor of plafter or of flightly 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 ftove must be employed to effect the drying. Laftly, the pieces of dried ftarch are fcraped, to remove the outfide cruft, which makes inferior ftarch, and these pieces are broken into fmaller pieces for fale. The grain which remains in the fack after the ftarch is extracted, contains the hufks and the glutinous part of the wheat, which are found very nutritious food for cattle.

The French manufacturers, according to Les Arts et Metiers, purfue 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 hufks of wheat. This water they prepare, by put ting a pailful of warm water into a tub, with about two pounds of leaven, such as some bakers ufe to make their dough rise or ferment. The water ftands two days, and is then stirred up, and half a pailful of warm water added to it; then being left to fettle till it is clear, it is poured off for ufe. 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 refufe wheat, and the other half bran. In this tub it continues to fteep and ferment during ten days, or lefs, according to the ftrength of the leaven-water, and according to the difpofition of the weather for fermentation. When the materials have been fufficiently fteeped, or fermented, an unctuous matter, which is the oil of the grain, will be feen fwimming on the furface, having been thrown up by the fermentation. This must be fcummed off; and the fermented grain, being taken out of the tub, is put into a fine hair-fieve, placed over a fettlingtub, when fair water is poured upon it, and washed through the fieve into the tub; by which means the ftarch is carried through the fieve with the water, of which about fix times the quantity of the grain are used.

The water ftands in the fettling-tub for a day, and becomes clear at top; when it is carefully laded out of the tub, leaving at the bottom a white fediment, which is the starch. The water which is taken off is four, and is called fure water: this is the proper leaven for the firft fteeping of the materials. The ftarch now obtained muft 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 fhovel, and then the tub is filled up with fair water. Two days after this, the water is laded out from the tub, and the ftarch appears in the bottom, but covered over with a dark-coloured 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 ftarch; and when this is done, about four inches of thick ftarch fhould 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 ftarch, ought to afford more, the whole being used, than the bran or husks; but the ftarch fo extracted is always of an inferior quality to that which is extracted from the bran of good wheat, particularly in the whitenefs of its colour. The starch in the different tubs is brought together into one, and there worked up with as much water as will diffolve it into a thin pafte, which is put into a filk fieve, and ftrained through with fresh water. This water is settled in a tub, and afterwards poured off, but before it is fo completely fettled as to lofe all its white colour: this renders the ftarch which is depofited ftill finer and whiter, and the ítarch which is depofited by the water so poured off is of a more common quality.

The ftarch thus purified is taken out of the bottom of the tubs, and put into wicker-baskets, about 18 inches long and 10 deep, rounded at the corners, and lined with linen cloths, which are not faftened to the bafkets. The water drips from the ftarch through the cloths for a day, and the baskets are then carried up to apartments at the top of the houfe, 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 plafter-floor, and the linen cloths, not being fattened to the bafkets, follow the starch, and, when taken off, leave loaves, or cakes of ftarch, which are left to dry a little, and are then broken into fmaller pieces, and left on the plafter-floor till very dry. But if the weather is at all humid, the ftarch is removed from the plaster-floor, and fpread out upon fhelves, in an apartment which is warmed by a ftove, and there it remains till perfectly dry. The pieces are afterwards scraped, to remove the outfide cruft, which makes common ftarch; and the fcraped 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 ftarch must be turned over every morning and evening, to prevent it from turning to a greenish colour, which it would otherwife do.

Thofe manufacturers who are not provided with a stove, make ufe of the top of a baker's oven to fpread the starch upon; and after being thoroughly dried here, it is ready for fale.

Starch may be made from potatoes, by foaking 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 fame time, another clean tub must be provided; and a hair-fieve, not too fine, must be fupported over it by two wooden rails extended across the tub. The pulp and water are thrown into the fieve, and the flour or ftarch is carried through with the water; fresh water muft then be poured on, till it runs through quite clear. The refufe pulp which remains in the fieve, 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 paffed through the fieve is turbid, and of a darkish colour, from the extractive matter which is diffolved in it. When it is suffered to rest for five or fix hours, all this matter depofits or fettles 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 ftirred up: it is then fettled for a day, and the water being poured off, the flour will be found to have again fettled in a whiter ftate. But to improve it, another quantity of water is poured on, and mixed up with it; in which state it is paffed through a fine filk-fieve, to arreft any fmall quantity of the pulp which may have escaped the firft hair-fieve. The whole muft afterwards be fuffered to ftand quiet, till the flour is entirely fettled, and the water above become perfectly clear; but if the water has any fenfible colour or tafte, the flour must be washed again with fresh water, for it is abfolutely 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 fhovel, and placed upon wickerframes covered with paper, to be dried in fome fituation properly defended from duft.

When the manufacture of ftarch from potatoes is attempted in a large way, fome 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 ftructure it refembles a large coffee-mill: the grater confits of a cone of iron-plate, about feven inches in diameter, and eight inches in height, the exterior surface of which is made toothed, like a rafp, by piercing holes through the plate from the infide. 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 withinfide like the outside of the cone; the fmallest end of the interior cone being uppermoft, 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 outfide of the cone and the infide 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 clofe to the interior diameter of the cylinder, the potatoes must be ground to a fine pulp before they can pass through between The machine, when at work, is placed in a tub filled with water; and as faft as the grinding proceeds, the pulp mixes regularly with the water, ready for the procefs before defcribed.

Mr. Whately of Cork has alfo proposed a mill for the fame purpose, on a different plan. The grater is a cylinder, with its axis horizontal, and turned by a handle at one end, with a fly-wheel to regulate the motion. A hopper is placed over the cylinder, into which the potatoes are thrown, and are grated by refting upon the cylinder, as it revolves round. There is alfo an horizontal box oppofite to the cylinder, into which the potatoes are received from the hopper, through a fliding-door; and a moveable end, which is fitted to the box, is preffed forwards towards the cylinder by a lever and weight, fo as to force the potatoes contained in the box against the cylinder, which, being kept in conftant motion, grates away the potatoes into a pulp with great rapidity, and it falls into a box beneath.

In the year 1796, lord William Murray obtained a patent for manufacturing ftarch from horfe-chefnuts. The method was to take the horse-chefnuts out of the outward green prickly hufk, 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 chefnuts perfectly white, and without the fmalleft fpeck. In this ftate the nuts were rafped or ground to a pulp with water, and the pulp washed with water through a coarse horse-hair fieve, and twice afterwards through finer fieves, with a conftant addition of clear cold water, till all the ftarch was washed clean from the pulp which remained in the fieve; and the water being fettled, depofited the ftarch, which was afterwards repeatedly washed, purified, and dried, in the fame manner as the potatoe-ftarch before described. We are not informed if this manufacture has been carried into effect.

The four, naufeous, milky liquor obtained in the procefs of ftarch-making, appears, upon analyfis, to contain acetous acid, ammonia, alcohol, gluten, and phofphate of lime. The office of the acid is to diffolve the gluten and phosphate of lime, and thus to feparate them from the ftarch.

Starch is ufed along with fmalt, or ftone-blue, to ftiffen and clear linen. The powder of it is also used to whiten and powder the hair.

It is alfo ufed by the dyers, to dispose their stuffs to take colours the better.

Starch is fometimes ufed inftead of fugar-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 alfo ufed medicinally for the fame intentions with the viscous fubftance which the flour of wheat forms with milk, in fluxes and catarrhs, under various forms of powders, mixtures, &c. A drachm of ftarch, with three ounces of any agreeable fimple water, and a little fugar, compofe an elegant jelly, of which a spoonful may be taken every hour or two. These gelatinous mixtures are likewife an useful injection in fome diarrhoeas, particularly where the lower inteftines have their natural mucus abraded by the flux, or are conftantly irritated by the acrimony of the matter. Starch is the common vehicle for the exhibition of opium per anum. By 43 Geo. III. c. 68. fched. (A), upon every hundred weight of ftarch imported a duty is impofed; and by 49 Geo. III. c. 98. fched. (A), a further duty upon every hundred weight is impofed.

No perfon fhall be a maker of ftarch within the limits of the head-office of excife in London, unless he occupies a tenement of 10l. a year, or upwards, for which he shall be affefled in his own name, and alfo pay to the poor-rates; nor elsewhere, unless he pay to the church and poor; or if there are no fuch rates, to the rate on houfes and windows, under the fame penalty as for making ftarch without entry. (19 Geo. III. c. 40. f. 3. 26 Geo. III. c. 51. f. 20.) By 43 Geo. III. c. 69. fched. (A), every flarch-maker fhall take out a licence, for which he fhall pay 51., and renew the fame annually within ten days before the end of the year, on pain of 30l. 24 Geo. III. c. 41. feff. 2.

Places of making ftarch are to be entered, under penalty of 200l. (24 Geo. III. c. 48. feff, 2.) All rooms and places, veflels and utenfils, fhall be marked and numbered, on the penalty of 50l. (19 Geo. III. c. 40. f. 12.) Flour, and other materials, found in any private place, and all private utenfils and veffels for making or keeping ftarch, unentered, shall be forfeited, or their value. (10 Ann. c. 26. f. 22.) Every ftarch-maker shall caufe his name to be painted over his door, or on fome confpicuous part of the front of his house, with the addition of flarch-maker, on penalty of 100%. (24 Geo. III. c. 48. feff. 2.) Officers may at all times enter and furvey, and make return to the commiffioners, leaving a true copy of the quantity, if demanded, under his hand, with the maker; and if he leave not fuch copy, after it has been demanded in writing (12 Geo. I. c. 28.), he fhall forfeit 40s. (10 Ann. c. 26. f. 14.) Notice of emptying the vats, and of taking the waters out of the tubs, fhall be given, on pain of forfeiting 100l. (19 Geo. III. c. 40.) The maker fhall ufe regular, fquare, or oblong boxes only, for boxing and draining his green ftarch, before it is dried in the ftove, on pain of 10l.; and give notice of boxing, and an account of drying, &c. Nor fhall he remove any ftarch after it is dried, before it be weighed, &c. by the officers, on pain of 200l. (4 Geo. II. c. 14. 19 Geo. III. c. 40.) All starch, before it be put into any ftove or place to dry (except for crufting), fhall be put in papers, tied up with ftrings, pafted over with a piece of paper of a different colour, and ftamped by the officer, under penalty of 100l. (26 Geo. III. c. 51.) Forging or ufing forged ftamps incurs a forfeiture of 500l. (26 Geo. III. c. 51.) The maker fhall have juft fcales and weights, on pain of 10l.; and if he fhall ufe infufficient fcales or weights, he fhall forfeit 100l. (10 Geo. III. c. 44.) Removing ftarch before due notice is prohibited by 10 Ann. c. 26. f. 19. And if it be removed before it is weighed by the officers, the perfon fo offending fhall forfeit 200l. (19 Geo. III. c. 49.) And if any dealer in ftarch fhall receive more than 28 lbs. not duly marked, he fhall forfeit 200l. 24 Geo. III. c. 48. 10 Ann. c. 26. s. 16.

Člandeftine manufacture, or concealing of ftarch, expofes the party concerned, unless he can make it appear that the B 2 duty

« ZurückWeiter »