33S

DYEING AND CALICO PRINTING.

disappear by the a&ion of light. Hydrated oxide of chromium yields an olivecolour. All these colours are characterised by their looseness, and by beingreadily affected by all kinds of reagents; they do not stand soaping, or evenordinary washing with soap. The Brazil wood reds are rendered a violet-blueby alkalies, while acids turn them yellow.

In calico dyeing and printing the red woods are used in connection withgarancin, as well as for the purpose of sightening the mordants temporarily.The decoctions and extracts are frequently used for producing steam-reds :the properly thickened liquor is mixed with — (i), acetate of alumina;(2), protochloride of tin and oxalic acid; (3), a salt of copper (chiefly theacetate), destined to promote oxidation during steaming. A good steam-red can be made with a mixture of Brazil wood liquor with chloride ofaluminium and chlorate of potash. The chloride of aluminium is decomposedby drying, and hydrochloric acid is given off, which reacts on the chlorate ofpotash, liberating chloric acid, which oxidises the colouring matter, the ulti-mate result being a compound of alumina with oxidised colour. This red isverj' fast. These steam-colours contain, therefore, in solution all the mate-rials required to form a red lake, which, by the steaming, is precipitated aswell as fixed upon the fibre.

The following are some of the reds and rose-reds used for steam and spiritcolours upon calico :—

Deep Red for Machine-work and Steaming. —9 litres of a decocftion ofSt. Martha wood, sp. gr. 1*022 ; 1 litre of berry liquor, sp. gr. 1*060 ; 1*5 litresof red liquor; 1*5 kilos, of starch; 125 milligrms. of a solution of nitrate ofcopper, sp. gr. 1-532.

Steam Rose-Red , upon Previously Mordanted % Cloth. —2-5 litres of liquor,sp. gr. 1-022 ; 5-5 litres of water ; 3 kilos, of gum ; 300 grms. of solution forrose-red (see immediately below) ; 50 grms. of nitrate of copper, sp. gr. 1*618.

The Tin Solution for Rose-Red is made up of—12 kilos, of nitric acid, sp. gr.1*334; 3' 2 5 kilos, of water; 1-25 kilos, of sal-ammoniac; 2*5 kilos, of bi-chloride of tin ; 1*5 kilos, of pure tin (either Banca or Cornish).

Spirit-Red. —5 kilos, of decoCtion of St. Martha wood, sp. gr. 1*022 ; boiltherein 0-25 kilo, of gum tragacanth, and add 600 grms. of bichloride of tin,sp. gr. 1*532 ; 180 grms. of salt for rose-red ; 150 grms. of nitrate of copper,sp. gr. 1*532; 2*i kilos, of tin solution as for rose-red. This colour is not tobe steamed, but becomes fixed by keeping the cloth hung up in a suitableroom.

Spirit-Rose is made up of 1 kilo, of the red mixture above mentioned and of1*5 kilos, of gum tragacanth water. It is usual to apply a mixed mordant'forthese colours,—that is to say, tin and alumina mixed, or each of these sepa-rately; oxide of tin yields better colours on cotton than alumina.

Woollen tissues which are to be dyed with red woods are first mordantedwith protochloride of tin or an aluminous compound. For a quantity of10 kilos, of wool, 1 kilo, of cream of tartar and 2 litres of a so-called redsolution are taken ; the wool is put in this mixture, and kept boiling for anhour. The red solution consists of 8 litres of water, 400 grms. of commonsalt, 1*25 kilos, of tin, and 8 litres of nitric acid. The alum-bath suitable for10 kilos, of wool consists of 2 kilos, of alum and 20 grms. of sulphuric acid.The woollen goods are left boiling an hour.

The employment of the red woods, at least for the production of red steam-