The art of dyeing the colour purple in ancient times is at- ributed to the Phoenicians. From their country it spread o Egypt, Israel, Crete and Mesopotamia to Greece and Rome. The pigments for purple dye were obtained from sixteen different kinds of sea snails which all belong to he Murex family in the Mediterranean Sea. It was a com- plex dyeing process, and for that reason purple-coloured fabric was rare, precious and reserved to men of power and wealth. Also for this reason this kind of purple was called “Imperial Purple” and “Tyrian Purple”, named af- er the Phoenician capital of Tyros. After the Roman Em- pire, imperial purple became the most important sym- bol of power. It was the time of the Byzantine culture. Afterwards, the use of Murex snails to obtain the impe- rial purple pigments was abandoned.' Similar pigments were used for dying fabric, though without achieving the original beauty of imperial purple. In the middle of the 19th century, British chemist Henry Perkin invented by accident the first synthetic dye named Mauveine which achieves the similar colour result on dyeing fabric like Fig.1: Fabric swatches in different tonalities of purple. Photo: Dorothea Nicolai. Fig.2: Murex trunculus. Photo: Dorothea Nicolai. The visible definition of purple is not clear. This col- our has various tonalities between bluish red and red- dish blue. In 1672 Isaac Newton discovered that other than the spectral colour of violet with its wavelength of approximately 380-420nm (Ktippers 2012: 31), purple is simply a secondary colour, the mix of red and blue, the longest (perceived by the L cone cells in the eyes) and the shortest wavelengths (perceived by the S cone cells in the eyes). The most intense purple nuances form the “line of purple” known as the “purple boundary” on the CIE 1931 colour chart, which represents all visible Fig.3: Chemical formula of Dibromindigo 6.6’ by Paul Friedlander 1919. Photo: Gerrit Holz. The Roman Empire Fig.5: Samit d‘Aix-la-Chapelle: Chart from approx. 800 AD, from the Trésor d*Aix-la-Chapelle; samit fragment depicting a victorious charioteer in the hippodrome (75 x 72.5 cm); Paris, Musée de Cluny — Musée National du Moyen Age CL 13289 / 09-501164. Druckdatei online auf www.photo.rmn.fr. Some of the traditions revolving around imperial purple Fig.6: “Mademoiselle Sicot” by Pierre-Auguste Renoir (1841- 1919), 1865, oil on canvas, 116x89.5 cm; Chester Dale Collection, 1963.10.209, National Gallery of Art, Washington, D.C. Available for free at www.images.nga.gov. The colour purple returned to European fashion in 1856 under the name of mauveine. A young British chemist, William Henry Perkin, invented this colour by accident during his research to synthesize quinine. He oxidized aniline using potassium dichromate producing a dark- coloured solid. While cleaning the flask he discovered that this solid mixed with alcohol became a rich purple-
