Important: Safety Warning
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.
Home › The Art Of Dyeing › To make Sulphate of Indigo
To make Sulphate of Indigo
Into 5 pounds of the most concentrated sulphuric acid, stir in by degrees 1 pound of the best indigo, finely ground; expose this mixture to ture to a heat of about 160° Fahr. for 10 or 12 hours, stirring it occasionally; a little rubbed upon a window-pane should assume a purpleblue color. ticity.
Take