WHITE AND BLACK.
Science teaches that white is the source of light or the product of combination of all other colors, because the light of the sun, which is assumed to be white, when broken up by means of a prism, shows in its image reflected upon a white plain, the three primary, and three secondary colors with the uncounted number of intermediary products of combinations of fractions of the primary colors forming the transition from one to the other, which can be perceived by the eye but not exactly separated from one another, but may quantitatively determined to an approximate degree of accuracy. Black, on the other hand, is described as the absence of all light, and it is denied, therefore, by theory a place among the colors.
Practice asserts the direct contrary of the theory developed by science by way of conclusion. While philosophers assert that they have succeeded in producing white light by the combination of lights of the various colors, for which combination, however, they give no formula, no dyer with the greatest patience and with the most subtile proportioning of dyestuffs, giving pure reproductions of the primary colors as seen in the spectrum or image of the broken sunbeam, can ever be able to produce anything of a color approaching white. But every dyer knows how to produce white by bleaching, that is, by the destruction of all color. And this operation is comparatively simple and easy to perform, since the great achievements of modern chemistry have placed into the hand of the dyer the most energetic and effectious color destroying agents. The ostrich feather dyer of to-day is able to convert naturally gray and even black feathers into nearly pure white, which undertaking his father would have called the boast of a deranged mind and an absolute physical impossibility. And with the aid of a complementary color dyed upon the bleached feathers the tint remaining upon them is obliterated, or neutralized, which operation is generally called "white dyeing," although certainly white cannot be "dyed" with a blue or violet dyestuff as little as blue or violet can be produced with a yellow dyestuff.
Black, on the other hand, although the name and rank of a color is denied it by the doctrines of theory is, for the dyer, most essentially a color requiring for its production the contribution of all colors, as can be shown by a simple experiment. If, for instance, within a circle, three equal circles, whose diameters are greater than half the diameter of the surrounding circle, are printed, one blue, one red and one yellow, so that the points of contact with the periphery of the outer circle are equidistant from one another, or form a regular triangle, their segments overlapping one another form four spherical triangles, one violet where red and blue cover one another, one orange where red and yellow come together, one green where yellow and blue are mixed, but the fourth is the centre, where parts of the three differently colored segments cover one another, is black, but toned by the color of the greatest intensity. In fact, black requires for its production more color, and is more difficult to dye than any color of the spectrum. It is not strange, therefore, that many more methods have been proposed and have been tried and adopted to dye black than for the production of any other color. Yet all these blacks are more or less tinted and are nothing more than the deepest shade, which can be produced with the aid of metallic salts, of blue, brown, gray, violet, green and even red. The only black upon ostrich feathers which may be justly called an absolute black is that produced after the method of Mr. Paul, as described in the front part of this book (page 53-56). It presents, besides, the advantage, that it can be completely done in eighteen minutes, while there are older methods which require not less than three days. Such, of course, will find no room here, but only the most reliable and expeditious, and safest of the older methods will be selected with due regard both to beauty of color and preservation of the precious material.