Do-it-yourself imperial purple

A British amateur chemist has worked out how the ancient Romans dyed the togas of emperors this deep colour thanks to a bacterium found in cockles from the supermarket Tesco. . .

With help of researchers in Reading and from Israel he has been able to establish the vital role played by a bacterium in chemically reducing (the addition of electrons) the ancient pigments so that they will dissolve in a dye solution. . .

The cockles are thought to harbour a bacterium that is crucial in reducing the dye. Wood ash was added to the vat to ensure the mixture did not turn acidic.
The mixture was then kept at 50 Celsius for about 10 days.

Wool dipped in the pigment turned green at first but, eventually, in contact with light, it turned purple.

Posted by David on September 15, 2003 2:28 PM