Color from St. Johns Wort.

Scientific American 12, 11.12.1847

The Massachuseetts Ploughman says "the flowers and tops of this plant contains a juice soluble in water, spirits of wine, or vinegar. With the first two liquids it forms a red color, resembling blood, and the latter a splendid crimson; when alum and a portion of potash are added to a strong solution of juice in water, it becomes a permanent yellow dye for cloth, cotton, paper &c.,

Would it not be better to use the alum, as a mordaunt, then clear up with the potass.
—ED.