ANTHOTYPE An obsolete " nature printing " process in vented by Sir John Herschel and founded upon the sensitiveness of juices of plants. Chevreul and Hunt also experimented in the same direc tion. The expressed juices, and alcoholic or watery infusions of certain flowers, more par ticularly papaver rhceas and corchorus japonica, were spread on paper and printed upon under a negative. Herschel found that the most sensitive colour was the yellow tint of the japonica, and that the blue tincture of the double purple groundsel completely bleached in the sunshine. According to his original instruc tions, published in 1842, the petals of fresh and well selected flowers are bruised to a pulp in a marble mortar, either alone or with a small quantity of alcohol, and then are squeezed through fine linen. The paper to be treated is moistened at the back with water, by sponging and blotting off, and pinned to a board, moist side downwards. The alcoholic tincture (mixed with a very little water if necessary) is then applied with a brush, in strokes from left to right. Then with a sweeping movement carry
the strokes up and down so as to cover the paper completely and leave no spaces. The paper is dried quickly, over a stove or otherwise. Papers so prepared generally require an exposure under a negative of about three or four weeks, and the pictures are not permanent. Herschel found that similar effects could be produced by light on the gums, resins, and residues of essen tial oils, when thin films were spread on metal plates ; also that a paper coated with an alcoholic solution of guaiacum, and placed in an aqueous solution of chlorine, acquired a beautiful blue colour, and could be used for copying engravings. All images by these processes quickly fade, and are of no value except as curiosities while they last. (See also " Nature Printing.")