Important: Safety Warning
This page contains a formula or preparation using substances now known to be dangerously toxic, such as arsenic, mercury, lead, or cyanide compounds. Exposure to these substances can cause severe poisoning, permanent injury, or death.
In addition, this page describes trade processes that use dangerously toxic materials such as cyanide solutions, mercury amalgams, or strong acids. These processes require training, equipment, and precautions far beyond what the text describes.
This information has been left in for historical purposes but should not be acted upon.
Green Ink
Dissolve 180 grains bichromate of potassa in 1 fluid ounce of water; add, while warm, 1/2 ounce spirit of wine then decompose the mixture with concentrated sulphuric acid, until it assumes a brown color; evaporate this liquor until its quantity addition makes the ink which was previously is reduced to one-half; dilute it with 2 ounces proof against alkalies, equally proof against distilled water; filter it, add 1/2 ounce alcohol, acids, and forms a writing fluid which cannot followed by a few drops strong sulphuric acid; be erased from paper by any common method it is now allowed to rest, and after a time it of fraudulent obliteration without the destruction of the paper. This ink writes greenish blue, but afterwards turns intensely black. 2490. Precautions in Making Writing Fluids. All the preceding receipts for writing fluids, under proper management, produce excellent products. Care must be taken in all cases that the ingredients be pure, and unless this precaution is attended to, success is doubtful. Either of the preceding blue fluids may be used as indelible ink to mark linen, and will be found very permanent, provided the part be first moistened with alum water and dried.