402

DYEING AND CALICO PRINTING.

of crystals of soda (carbonate), in 4000 kilos, of water, for a quarter of anhour, and next 61 kilos, of concentrated sulphuric acid are added, and themixture boiled for three-quarters of an hour, and afterwards washed andpressed.

M. G. Schaeffer boils 100 parts of pulverised quercitron with 280 parts ofwater and 25 parts of concentrated sulphuric acid.

M. Schlumberger prefers 100 parts of quercitron, 300 of water, and 15 ofacid: 100 parts of quercitron yield 85 parts of what is termed “commercialquercetin,” which has as much tinctorial value as 250 parts of quercitron.*

This material (viz., the commercial quercetin) possesses the following advan-tages over the quercitron:—(1). The removal of the tannin contained in thequercitron, whereby the injurious action of that tannin upon the brightness ofthe colour is prevented. (2). An absolute gain as to colouring matter isobtained. (3). The shades produced on the textile fabrics are more full-bodiedand livelier. On the other hand, dyeing with this preparation requires ahigher temperature (ioo°) than quercitron ; the portions intended to be keptwhite are more soiled; the shades produced are more fugitive; and, lastly,owing to the insolubility, or at least sparing solubility, of the quercetin, nodecoCtions of the commercial quercetin can be made. M. Schlumberger hasfound, however, that boiling with dilute sulphuric acid, applied to other yellowcolouring matters,—as, for instance, sumach, weld, Persian berries, fustic,turmeric,—yields excellent results, as far as the brightness of the colours pro-duced and the productivity of the ware are concerned ; so that, just as in caseof quercitron, there are obtained, by the above treatment, preparations ofabsolutely increased tinctorial value.

The most important commercial preparation of quercitron is flavin, a dye-ware about which there is no little mystery,—due, perhaps, to the faCt that thename has been given to a variety of bodies obtained by totally different pro-cesses. English made flavin is obtained by dissolvingout the colour of quercitronin weak alkaline solutions, and precipitating by the addition of sulphuric orhydrochloric acid. It is sometimes adulterated with common salt to theextent of 8 per cent. There are again flavins so-called, imported fromAmerica, which appear to be merely bark, mechanically purified by a processof thrashing and sifting. The superior American flavin is said to be madeby cutting up the perfectly fresh bark, freed from its epidermis, and extractingit with steam at a temperature of 102° to 103° C. The condensed water con-tains the flavin partly in solution and partly in suspension. Several patentsfor the manufacture of flavin have been taken out in the United States.Some flavins, on chemical examination/ prove to be nearly pure quercitrin,and others nearly pure quercetin, a faCt which proves want of uniformity inthe mode of preparation. Good flavin has about sixteen times the tinctorialvalue of quercitron bark.

For the purposes of calico-printing either the freshly-prepared decoCtions ofquercitron are used, or liquid extracts of a specific gravity varying from 1*070to 1*152, and known as bark liquor, or the substance known as flavin, andimported from America in the form of an olive-yellow powder.

Quercitron and its commercial derivatives yield, to mordanted calico, theundermentioned shades:—With aluminous mordants, canary-yellow; with

+ “ Bulletin de la Societe Industrielle de Mulhousc,” vol. xxvii., p. 411.