Indigo Plantation
Before the Portuguese, who were the first Europeans in India, traded with India there was extensive trading for centuries by the Arabs between the west coast of India and southern Europe. The Indigo plant or dye was one of the items of trade.
These dyes - brilliant purple and reds - were very expensive and only the Roman Emperors and the very wealthy could afford them hence the term "the royal purple". The range from deep red to purple to deep blue can be obtained by adjusting the pH (acidity - alkanility) of the solution. It was the Portuguese who gave the dye or plant the name "Indigo" meaning "from the indies". The Arabs called the dye "a-nil" meaning "the blue" - they just used the adjective and left out the noun. "Nil" is blue in Sanskrit as in the Nilgiri Hills in Southern India which translated means the "Blue Hills" as they look blue from the plains due to the combination of mist and heavy rain forest.
In the late 1800's the Germans - and later the British - synthesized these indigo dyes chemically and used the original arab or Sanskrit name in calling them "anilin dyes" which is the term used in chemistry books. Unfortunately the chemical synthesis of these dyes by the Europeans effectively destroyed the indigo industry in India. During World War II in India we couldn't get the synthetic dyes or fabric from England; instead we used Indian fabrics dyed with the Indian indigo dyes.
External Links
Historical Books Online
Tent Life in Tigerland with which is incorporated Sport and Work on the Nepaul Frontier : being twelve years' sporting reminiscences of a pioneer [indigo planter in an indian frontier district by James Inglis 1892