Starch from certain foreign plants

—1. From the pith of the sago palm . See Sago . 2. From the roots of the Maranta a rund in ace a , of Jamaica, the Bahamas, and other West India islands, the powder called arrow-root is obtained, by a proce analogous to that for making potato starch. 3. From the root of the Manioc , which also grows in the West Indies, as well as in Africa, the ca ava is procured, by a similar proce . The juice of this plant is poisonous, from which the wholesome starch is deposited. When dried with stirring upon hot iron plates, it agglomerates into small lumps, called tapioca ; being a gummy fecula. The characters of the different varieties of starch can be learnt only from microscopic observation; by which means also their sophistication or admixture may be readily ascertained. Starch, from whatever source obtained, is a white soft powder, which feels crispy, like flowers of sulphur, when pre ed between the fingers; it is destitute of taste and smell, unchangeable in the atmosphere, and has a specific gravity of 1·53. I have already described the particles as spheroids enclosed in a membrane. The potato contains some of the largest, and the millet the smallest. Potato starch consists of truncated ovoids, varying in size from 1 ⁄ 300 to 1 ⁄ 3000 of an inch; arrow-root, of ovoids varying in size from 1 ⁄ 800 to 1 ⁄ 2000 of an inch; flower starch, of insulated globules about 1 ⁄ 1000 of an inch; ca ava, of similar globules a embled in groups. These measurements I have made with a good achromatic microscope, and a divided gla -slip micrometer of Tully. For the saccharine changes which starch undergoes by the action of diastase , see Fermentation . Lichenine , a species of starch obtained from Iceland mo ( Cetraria islandica ), as well as inuline , from elecampane ( Inula Helenium ), are rather objects of chemical curiosity, than of manufactures. There is a kind of starch made in order to be converted into gum for the calico-printer. This conversion having been first made upon the great scale in this country, has occasioned the product to be called British gum. The following is the proce pursued in a large and well conducted establishment near Manchester. A range of four wooden cisterns, each about 7 or 8 feet square, and 4 feet deep, is provided. Into each of them 2000 gallons of water being introduced, 12 1 ⁄ 2 loads of flour are stirred in. This mixture is set to ferment upon old leaven left at the bottom of the backs, during 2 or 3 days. The contents are then stirred up, and pumped off into 3 stone cisterns, 7 feet square and 4 feet deep; as much water being added, with agitation, as will fill the cisterns to the brim. In the course of 24 hours the starch forms a firm deposit at the bottom; and the water is then syphoned off. The gluten is next scraped from the surface, and the starch is transferred into wooden boxes pierced with holes, which may be lined with coarse cloth, or not, at the pleasure of the operator. The starch, cut into cubical ma es, is put into iron trays, and set to dry in a large apartment, two stories high, heated by a horizontal cylinder of cast-iron traversed by the flame of a furnace. The drying occupies two days. It is now ready for conversion into gum, for which purpose it is put into oblong trays of sheet iron, and heated to the temperature of 300° F. in a cast-iron oven, which holds four of these trays. Here it concretes into irregular semi-transparent yellow-brown lumps, which are ground into fine flour between mill-stones, and in this state brought to the market. In this roasted starch, the vesicles being burst, their contents become soluble in cold water. British gum is not convertible into sugar, as starch is, by the action of dilute sulphuric acid; nor into mucic acid, by nitric acid; but into the oxalic; and it is tinged purple-red by iodine. It is composed, in 100 parts, of 35·7 carbon, 6·2 hydrogen, and 58·1 oxygen; while starch is composed of, 43·5 carbon, 6·8 hydrogen, and 49·7 oxygen. To prove whether starch be quite free from gluten, or whether it be mixed with any wheat flour, diffuse 12 grains of it through six ounces of water, heat the mixture to boiling, stirring it meanwhile with a gla slip. If the starch be pure, no froth will be seen upon the surface of the pasty fluid; or if any be produced during the stirring, it will immediately subside after it; but if the smallest portion of gluten be present, much froth will be permanently formed, which may be raised by stirring into the appearance of soap-suds. IMG:4147767755307473660_illo1167.png:Steam-drying apparatus Figs. 1049, 1050 enlarged (177 kB) STARCHING and Steam-drying Apparatus . The system of hollow cylinders, for drying goods in the proce es of bleaching or calico-printing, is represented in fig. 1049. in a longitudinal section, and in fig. 1050. in a top view; but the cylinders are supposed to be broken off in the middle, as it was needle to repeat the parts at the other end, which are sufficiently shown in the section. A is the box containing the paste, when the goods are to be starched or stiffened: a , a winch, when it is desired to turn the machine by hand, though it is always moved by power in considerable factories; b , is the driving pinion; d , d′ , two bra rollers with iron shafts, the undermost of which is moved by the wheel c , in geer with the pinion b . The uppermost roller d′ , is turned by the friction with the former, d , being pre ed upon it by the weighted lever h ; e is the trough filled with the paste, which rests upon the bars f , and may be placed higher or lower by means of the adjusting screws g , according as the roller d is to be plunged more or le deeply. A bra roller i serves to force down the cloth into the paste. B , is the drying part of the machine: k , k , its iron framing; l , l , ., five drums, or hollow copper cylinders, heated with steam: m , m , m , ., small copper drums, in pairs, turning freely on shafts under the former, for stretching the goods, and airing them, during their pa age through the machine: n , n , is the main steam-pipe, from which branch off small copper tubes, o , o , ., which conduct the steam through stuffing-boxes into the cavity of the drying-drums. There are similar tubes upon the other ends of the drums, for discharging the condensed water through similar stuffing-boxes: q , q , are valves, opening internally, for admitting the air whenever the steam is taken off , or becomes feeble, to prevent the drums from being crushed by the unbalanced pre ure of the atmosphere upon their external surfaces. C , is the cloth-beam, from which the starching roller draws forward the goods; d , d , are two rollers, of which the lower is provided with a band-pulley or rigger, driven by a similar pulley fixed upon the shaft of the starching roller d . These two rollers pull the goods through the drying machine, and then let them fall either upon a table or the floor.