At Manchester the black pattern is printed-on with a mixture of iron
liquor and extract of logwood, and the resist paste by the cylinder
machine; in France the black is given by the following recipe:--
Take 1 gallon of decoction of galls of spec. grav. 1·04, mixed and
boiled into a paste with
14 ounces of flour; into the paste, when nearly cold, there are
added,
8 ounces of an acetated peroxide of iron, made by adding 1 lib.
acetate of lead to 3
libs. of nitrate of iron, spec. grav. 1·56.
1/8 ounce of gallipoli oil.
This topical black forms a fast colour, and resists the fine blue vat,
weak potash lye, bichromate of potash, boiling milk of lime, dunging and
maddering.
The preceding answers best for the block; the following for the
cylinder,--
2. Take 1 gallon decoction of galls of spec. grav. 1·056.
18 ounces of flour, mix, boil into a paste, to which, when cool,
add
8 ounces of the aceto-nitrate of iron of the preceding formula, and
1 quart of iron liquor of spec. grav. 1·110.
In Lancashire a little prussiate of potash is sometimes added to nitrate
of iron and decoction of logwood; and the goods are after washing, &c.
finished by passing through a weak solution of bichromate of potash. The
chromic acid gives depth and permanence to the black dye, being supposed
to impart oxygen to the iron, while it does not affect any of the other
colours that may happen to be impressed upon the cloth, as solution of
chloride of lime would be apt to do. The solution of the bichromate
deepens the spirit purples into blacks, and therefore with such delicate
dyes becomes a very valuable application. This interesting fact was
communicated to me by an eminent calico-printer in Lancashire.
Having premised the composition of the topical black dye, we are now
prepared to apply it in the lazulite style.