If the copperas be partially peroxidized, somewhat more of it must be used.
The amount of copperas should be from one and a half to twice that of the indigo.
Then boil them, and put in a piece of copperas, as large as a hen's egg.
It was black, but the copperas would eat the paper after a while.
copperas is used in lager beer; tobacco, nux vomica, and cocculus indicus in London porter—brown stout.
Alum and copperas have been known in the Highlands long ages.
The copperas solution is easily prepared by hanging a basket containing about sixty pounds of copperas in a barrel of water.
Put the wool into this for 1/2 hour; then return it into the alum and copperas for 10 to 15 minutes.
Sweet-gum bark and copperas and make any cloth a purple color.
Miss copperas had said, when I hinted so to her on first trying it, that it wanted “age.”