500
DYEING AND CALICO PRINTING.
China Nut-galls. —More or less spherical in shape and irregular in sire,externally provided with conical points, internally hollow; averagesize that of a Barcelona nut. This kind of gall is formed upon aspecies of sumac, and is highly valued on account of its large per-centage of tannic acid.
Valonia Nuts, sometimes known as Levant Nut-galls, are imported intoEurope from Greece, Southern Italy, Smyrna, and other parts ofAsiatic Turkey ; the acorn-cup of a species of oak botanically knownas Quercus agilops. These cups have the shape of flowers, the acornbeing in the centre, and are readily detached from the fruit by a kind offermentation which the substance undergoes when laid up in heaps;the acorn having fallen out, the flower-like cup is dried, and is thenfit for the market.
Divi-divi, livi-divi, or libi-divi, is now one of the most important astringentsin the market. It consists of the pods of Ccesalpinia coriaria, a small treefound in the province of Maracaibo, and in other parts of South America.The pods are of different shades of brown, sometimes nearly black; they areabout 3 inches long and I inch broad, and are usually warped, twisted, or evendoubled up. The best pods are thick and fleshy, and of a pale colour. Thosewhich are very dark, with black spots and blotches, have probably beengathered in a damp state, or have been subsequently exposed to moisture,which greatly reduces their value. The amount of tannin in divi-divi isgreater than in sumac, or even myrobalans, but it is in the first-mentionedbody accompanied by a peculiar colouring principle, which limits the applica-tions of this ware. It is very largely used in producing a black upon thecotton warps of mixed goods. Divi-divi has another defedt: it is of a glutinousor adhesive nature, whence fragments of the ground pods are apt to cling tothe mordanted tissues, and when washed away are found to have played thepart of a resist, and protedted certain portions of the goods from the adtion ofthe tannin. Consequently, when the dyeing operations are completed thecloth appears speckled. Hence it is better to extradt the ware with water, andallow only the clear liquor to come in contadt with the goods. Divi-divi isgenerally the cheapest astringent.
Myrobalans, otherwise called myrabolans, or myrabolams, are the fruit ofTerminalia Chcbula, a tree common in some parts of India. In shape andsize myrobalans somewhat resemble shrivelled plums. They are of a palebuff colour, consisting of a dry pulp, varying in thickness, and enclosing astone-like kernel, which contains no tannin, and forms from 23 to 52 per centof the whole weight. The moisture present in the nuts, as found in commerce,varies from 3 to 7 per cent, and the amount of ash left on incineration is about10 per cent. The tannic acid is mainly present in the pulp. Good ungroundmyrobalans should be pale, plump, free from dark blotches and from worm-holes. They should be hard and firm, ringing like fragments of earthenwarewhen shaken together, and if crushed with a hammer yielding a dry, palepowder, mixed with hard irregular fragments. If they can be crushed to adark-coloured dust between the fingers, or if they work out into a paste underthe pestle, they are of poor quality. Ground myrobalans should form a palebuff powder, dry, astringent to the taste, but free from a saline flavour or fromintense bitterness. If moistened and rubbed in the hand, they should form avery tenacious paste.