CATECHU.
497
Catechu. 6 kilos.
Acetic acid, at 7 0 Baume (sp. gr. 1-048, containing about) l2 jj30 per cent of anhydrous acetic acid, at 15°) .. .. J
Water. 4 ,,
Thicken with gum ; steam, and pass through the bichromate bath.
Catechu. 10 kilos.
Pyroligneous acid.20 litres.
Solution of acetate of lime (sp. gr. 1-048) 5 „
This ingredient can only adt as a hygroscopic substance.
Solution of acetate of manganese (sp. gr. 1-246).. .. 3 ,,
This material modifies the hue or tint.
Gum . 7-5 kilos.
Again steaming, and oxidation by means of the bichromate.
Catechu. 3 kilos.
Pyroligneous acid. 6 litres.
Sal-ammoniac .360 grms.
Verdigris .31 „
Gum-water, made up with 700 grms. to the litre .. .. 6 litres.
Acetate of lime solution. 1-5 ,,
Fabrics dyed or printed with this mixture are not steamed, and not passed
through a chromate bath, but are first aged, and next passed through lime-
water (milk of lime).
Catechu Mixture for Madder Style.
Catechu. 14 kilos.
Water . 18 litres.
Sal-ammonia. 5 kilos.
Acetate of copper. 3'375 kilos.
Acetic acid (sp. gr. 1-048, containing about 30 per) litres
cent of anhydrous acid at 15°) . /
Solution of acetate of lime. 9 litres.
Gum. 15 kilos.
Pyrolignite of alumina in solution (sp. gr. 1-070) .. 1 litre.
After having been printed on the tissue, along with or next to the mordant,this mixture is fixed by ageing, next passed through the dung-bath, and after-wards dyed in madder. Where it is desired to have a catechu-dyed groundfour different processes may be employed :—
1. A mixture of an acetic acid decodtion of catechu and pyrolignite of ironis printed on and left exposed to air for twenty-four hours, after which time
■t is bichromated ; the decodtion is made up of—
Yellow catechu.too grms.
Water. .. 2 litres.
Acetic acid (sp. gr. 1-056, containing 37 per cent) I00 grms .
anhydrous acid at 15 0 ).. >
Gum. 1 kilo.
To every 10 litres of this standard mixture 1 litre of pyrolignite of iron( S P- gr. 1-070) is taken. When the colour is to be lighter 4 litres of gum