Question

How indigo was produced in 19 century

Answer 1

Indigo dye is an organic compound with a distinctive blue color (see indigo). Historically, indigo was a natural dyeextracted from the leaves of certain plants, and this process was important economically because blue dyes were once rare. A large percentage of indigo dye produced today, several thousand tonnes each year, is synthetic. It is the blue often associated with denim cloth and blue jeans.