If you are in a hurry for scarlet, you may drop the particles of block-tin into aqua-fortis till they are dissolved, and add a little to the scarlet dye; the other is best, as it gives a more brilliant shade;—boil slow.
If the extract of bismuth is added to the red liquor of the cochineal in a small quantity, it will change it to a purple or violet colour.
FOOTNOTES:
[I] Spirits of grain for scarlet,—a quarter pint of spirits of nitre, a quarter of an ounce of ammoniac, add half water in a bottle, and drop into it half an ounce of block-tin in grains till dissolved.
CRIMSON RED IN GRAIN.
Boil your hackles or hair in a quarter of an ounce of alum, and the same quantity of pure tartar, an hour gently; wash them out of this, fill your dye-pot with clean water, or as much as will conveniently boil; put in an ounce of well-powdered dye stuff they call "grain," with one drachm of red arsenic, and one spoonful of burnt wine lees, this gives a lustre; wash and rinse well after boiling a short time, and the colour is good.