ABSTRACT
Even in ancient times, attempts seem to have been made to improve the yellowish appearance of “ white” products, principally textiles. The first bleaching process put into practice may well have been bleaching in the sun (bleaching on grass). In the literature, it is reported that toward the end of the eighteenth century, extracts made from chestnuts were used to strengthen the action of bleach liquors. In 1919, Krais isolated esculin (Structure I) as the fluorescent substance from horse-chestnut extract and demonstrated that it made possible a marked improve ment in the whiteness of bleached linen yam and viscose artificial silk, though, unfortunately, the fastness properties to washing and light were unacceptable. Confirmation was thus afforded of the principal enunciated in 1921 by von Lagorio [1] that fluorescent colorations.reflect more visible light than they receive as radiation. Krais’ article, entitled “ Uber ein neues Schwarz und ein neues Weiss” [2] contains the historic proposition that even the whitest white can be made whiter.
