STARCH (FR., Ftrode, Amidon ; GER., Stlfrke).
The term " starch " is applied to the fecula or amylaceous.matter contained in the fruits, roots, or cellular tissue of by far the greater number of plants, and extracted from a few on a commercial scale. It occurs in grains of various sizes, Imviug when pure a slightly yellowish colour, awl whose form and structure are characteristic for each kind ; the bluish tint of laundry-starch is due to the addition of a mixture of smalt and alum in water : such starch ie considered unfit for dietetic or medioinal use. The sp. gr. varies with the kind of starch, and with its drynees ; the amount of water reaches 30 per cent. in some instances, and at times descends to 7 when air-dry. The formula is variously given as (0613.05)2 30112, CisH30015, and C361162031 -I- 120H, Some starches aro prepared for use as alimentary substances, while others sre only converted into an article for industrial application. The beet qualities of starch serve for sizing paper, espeoially fancy papers (see pp. 1489-90). The finest starch is used for the manufacture of white glucose syrups (see Sugar—Starch-sugar), for finishing textiles (see pp. 770-6, 1185), for making white dextrine (see pp. 1645-7), as well as for preparing farinaceous food and fine pastry. Inferior sorts are used for the eame purposes when the quality is not of auch importance, as for instance, for weavers' dressing, as a means of thickening mordants (see pp. 1293-1305), and colouring substances for cloth printing (see pp. 835-54). By fermentation, it produces glucose and then alcohol (see pp. 192-214). Another important application is the " dusting" of the forms in metal foundries, in lieu of charcoal dust. Its use for stiffening (" starching") linen and washed clothes is well known.
The principal kinds of starch will now he separately described. They can be distinguished under the microscope by the shape of the granules : in rice, they are small and angular ; in maize, angular but larger ; in wheat, lens-shaped; in potato, arrowroot, and tous-les-mois, more or less ovate ; in tapioca, n3uller-shaped. They vary in size from 2,4 to 10L0 in.
Arrowroot. —The name " arrowroot " embraces the amylaceous matter of several kinds of plant very widely disseminated in the tropics. The most important of these is Haranta arundinacea, a native of the W. Indies and Tropical America, from Mexico to Brazil, and occurring under the
form known as M. indica, which has narrower, sharper, and always smooth leaves, in Bengal, Java and the Philippines. It is also cultivated in Mauritius and Natal, and on the W. coast of Africa.
In Bermuda, arrowroot is planted in May and ripens in March-April ; it is manufactured in April-May, during the cold winds. The process is simple. The washed rhizomes are reduced to a pulp, which is strained through sieves of progressive fineness, allowed to settle, collected, passed through the finest sieve into clean water, settled, and the layer of brown colour removed from the surface. This brown starch is the more astringent of the two, and is locally preferred. After a final passing through the finest sieve, and settling, it is placed on cloths to harden, broken up fine on trays, and dried in the sun and wind. About 100 lb. good arrowroot may be got from 4 barrels of the peeled and cleaned rhizomes, about 24 hours being the duration of the water process. In Jamaica, rude machinery is used for the pulping operation. The one great precaution necessary is the absolute avoidance of contamination with dust, rust, insects, or anything capable of communi cating odour or colour ; hence a good supply of pure water (especially free from iron) is pre eminently requisite. • The refuse of the plant forms excellent pig-feeding material. The, pro duction and exports of arrowroot from the W. Indian Islands are exhibited in the following figures. Bermuda shipped 10,331/. worth in 1851, which gradually decreased till the quantity in 1870 was only 25 cwt. The quality of Bermuda arrowroot has never been surpassed, mainly on account of the care exercised in its preparation. Jamaica has about 50-60 acres under arrowroot ; the exports were 70,204 lb. in 1866, 13,193 in 1871-2, 1636 in 1873-4, 21,983 in 1874-5, 3514 in 1876-7. St. Vincent shipped 10,379 bar. in 1870, 17,669 in 1877, and 14,916 in 1879. Barbados exported 114/. worth in 1877, and 24/. in 1878. Grenada shipped 20 lb. in 1878. In the adjacent colony of British Guiana, the plant is readily cultivated, but the product is very inferior through carelessness in the preparation. Dutch Guiana (Surinam) exported 621i kilo. (of 2.2 lb.) in 1877, and 89 in 1878.