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DYEING AND CALICO PRINTING.

F. Rochleder,* and also Th. Martius Mayer. According to Dr. Rochleder itcontains pedtin, rubichloric acid, tannin, and a yellow colouring matter iden-tical with the crocin present in saffron (Crocus sativus). This pigment isobtained by exhausting the wongshy with boiling alcohol, and concentratingthe liquid by evaporation, followed by filtration. The alcoholic tindture is thendiluted with much water, and there is added gelatinous alumina. After a fewdays standing the liquid is again filtered, and the filtrate precipitated withacetate of lead. The precipitate thus formed is washed with cold water, and,after having been suspended in water, is decomposed by sulphuretted hydrogen.The colouring matter is extradled from the sulphide of lead by means ofalcohol, the liquid evaporated to dryness and taken up with water, by whichthe colouring matter is left undissolved as an amorphous rose-coloured body,about which more will be said under “ saffron.”

Wongshy is used in China for dyeing yellow, and also as a ground for greendyes, and for imparting a first colour to silk and cotton which are intended tobe dyed cherry-red, scarlet, or crimson, with safflower. The colours thus ob-tained are faster and brighter. Wongshy is not much used as a dye-materialin this country : it produces shades of yellow and orange upon woollen andsilk which do not appear to be possessed of much stability.

The late M. Persoz made some experiments with the colouring matter ofthe hoang-tchy, which he obtained from the late celebrated botanist Dr. Mar-tius. Persoz exhausted the fruit first with sulphide of carbon, which takes upa fatty matter ; next with wood-spirit (methylic alcohol), which dissolves thecolouring matter, leaving it on evaporation as a reddish crystalline residue,soluble in water. This colouring matter dyes cotton, mordanted with aluminaor oxide of tin, a yellow colour ; with oxide of iron an olive colour is obtained.This colouring matter dyes silk diredtly without any mordant. The decodtionof the fruit was used, and to each litre thereof were added 2 grms. of alumand 1 grm. of oxalic acid; temperature, 40° to 50°: the shade obtained ispure yellow, not affedted by acids or alkalies : wool is dyed similarly, with theaddition to the bath of a tin-salt, or the wool may be first alumed.

The name of hoang-tchi applies to the yellow colouring principle of saf-flower, which is extradted by first placing the safflower (previously tied in bags)in pure water, and squeezing it by stamping on it with the naked feet; and nextby placing it in sour rice-water. The yellow juice thus obtained is employed forimparting a ground to silk intended to be dyed scarlet and red. Since Chinesesafflower is not brought into commerce until after it has been treated as justdescribed, it is clear that the ware imported from China is almost entirely de-prived of its yellow colouring principle. According to the Chinese the fastnessand beauty of their safflower-dyed fabrics is due to the fadt that they first dyethese fabrics a yellow colour, as just mentioned.

Saffron.

What is known as saffron is the pistils and stigmata of the flower of theCrocus sativus , a bulbous plant of the liliaceous order, which is a native ofSouthern Europe, and cultivated—for its use in pharmacy and as a condiment—in Spain, Southern France, Austria, Greece, and England. This ware contains

t u Neues Repertorium fur Pharm.,” iv., 365—367. “ Dingler’s Polytechnisches Journal,cxiv., 136. “ Repertoire Chimie Appliq.,” i., 87.