34 §

DYEING AND CALICO PRINTING.

1-85 kilos.; sulphate of copper, 250 grms.; oxalic acid, 150 grms. In additionto the ingredients just named mordants are added, consisting of iron andalumina salts, or salts of tin : the addition of the salt of copper and of sal-ammoniac is oxidising. Instead of the salt of copper the sulphuret of thatmetal may be employed,.as proposed by M. Lauth.

Steam-Grey for Roller-Printing .—Water, 5 litres; pyroligneous acid, at 2°B.(sp. gr. 1*014), o*5 litre ; decoCtion of logwood, at 2 0 B. (sp. gr. 1*014), tV* 1litre ; quercitron decoCtion, of the same strength, -^th litre ; sal-ammoniac,0*25 kilo.; gum substitute, 1*5 kilos. To every litre of this mixture are added60 grms. of the undermentioned blue mordant, made up of—Ferrocyanide ofpotassium (yellow prussiate), 500 grms.; chlorate of potassa, 150 grms.;water, 0*75 litre; sulphuric acid, at 65° B. (sp. gr. 1*827), 640 grms., dilutedwith 0*12 litre of water: the acid and water should be mixed and left to coolbefore being added to the rest of the ingredients.

These steam-greys may be varied in divers ways ; for instance—LogwooddecoCtion at 2 0 B. (sp.gr. 1*014), 2*5 litres ; pyroligneous acid, at 2° B. (sp. gr.1*014), 1 litre; red liquor (mordant as used for madder colours), at 8° B.(sp. gr. 1*060), 2*5 litres ; water, 13 litres ; pyrolignite of iron, at io° B. (sp.gr.1*075), 2 *5 litres ; starch, 2*25 kilos.

Application-Grey. —Water, 1 litre. The following substances should bedissolved therein or added thereto :—Gommeline, 1 kilo.; solution of gumtragacanth, 0*125 kilo.; pyroligneous acid, at 3 0 B. (sp. gr. 1*022), 0*060 litre;solution of sulphate of iron, at 20° B. (sp. gr. 1*162), 0*18 litre [such a solutioncontains about 28 per cent of the crystallised salt] ; red liquor, as used formadder, 0*060 litre.

Logwood decoCtions also enter into the preparation of olive, reseda, oak-brown, and some other dyes. In dyeing wool and silk with logwood, blue isobtained on wool by mordanting it with alum and cream of tartar, and im-mersing the woollen material in a boiling bath of logwood, or extract thereof,to which sulphate of copper has been added,

For the so-called king’s blue the following quantities are used :—For100 kilos, of wool: alum, 10 kilos.; cream of tartar, 2 kilos.; sulphate ofcopper, 1 kilo.; shavings of logwood, r sufficient quantity.

Logwood is also employed for the production of French blue upon wool,along with indigo, santal, orchil, and nut-galls.

The well-known excellent Elbeuf and Sedan blacks, on broad cloth, aredyed first more or less deep blue, by means of the indigo vat, and afterwardsdyed black, in a boiling bath made up of logwood, sumach, and sulphate ofiron. If the cloth is not first indigo vatted, it is mordanted with alum andred argol, and dyed in a bath to which logwood, fustic, orchil, alum, argol,and copperas are added.

A fast black upon wool, which does not fade, is produced with logwood, whenthe woollen fabric is first mordanted with bichromate of potash and creamof tartar, and next dyed with logwood, orchil, and alum. On the Continentthe best blacks upon woollen tissues of superior description are very generallyobtained by means of madder.

The fastest logwood-black upon woollen and worsted goods is that obtainedby the old logwood and copperas process. It is now little used, not from anyimperfection in the results, but because it requires more time, labour, and