The results, for colors, are fairly satisfactory but are not so permanent as the dyeing process. In an oil paint the solid coloring matter, or pigment, is ground up finely in boiled linseed oil, an oil which has the property of drying to a firm varnish when exposed to the air. This mixture is thinned with turpentine or gasolene to the desired consistency before using. It is evident that, in coloring feathers, if enough oil is applied to fasten the pigment very firmly to the flues, there is danger at the same time of plastering the fine barbules so that they will never get back to their proper places, and the product will be hopelessly stringy. On the other hand, if the amount of oil is so small, thanks to the abundant thinning with gasolene, that there is no fear of its sticking the barbules together, there will hardly be enough oil left to firmly fasten the pigment to the flues, on drying, and the color is apt to rub, and to wear off quickly. Paint, thinned with gasolene, has been applied to feathers occasionally by means of stencils, some of the so-called “barred” effects, looking like the feathers from a barred Plymouth Rock hen, being made in this way—the color, black paint or varnish, greatly thinned, being applied by means of an “air brush” or atomizer. Occasionally very large, wide, and handsome feathers have appeared decorated with flowers and other figures, in bright colors, applied in the same way with an air brush, sometimes with the help of stencils, but generally free-hand. These effects are often rather crude and inartistic, but there is no reason why, skilfully used, this method of decorating the backs of feathers might not produce interesting effects. CHAPTER X LEATHER AND LEATHER DYEING So far as can be learned, in every part of the world, the first materials used by man for clothing and coverings were the skins of animals. In its natural condition, however, the hide stripped from a dead animal has certain properties which greatly interfere with such use. When dry it is stiff and hard; when moist it rapidly decomposes, and when exposed to hot water it swells and in time dissolves. These difficulties had to be overcome before skins and furs could be properly utilized. And, accordingly, in the history of every nation and race, one of the very earliest of all developing industries was the art of leather making; that is, of converting the hard and easily decomposed rawhide into a soft, pliable, and comparatively permanent substance, well suited for the use of man.