After-images play many subtle parts in painting. For example, in a painting where a gray-blue sky meets the horizon of a blue-green body of water, the involuntary eye-movements may produce a pinkish line just above the horizon. This is the after-image of the blue-green water creeping upward by eye-movements. Many vivid illusions of this character may be deliberately obtained by the artist. Some of the peculiar restless effects obtained in impressionistic painting (stippling of small areas with relatively pure hues) are due to contrasts and after-images. A painting came to the author's notice in which several after-images of the sun, besides the image of the sun itself, were disposed in various positions. Their colors varied in the same manner as the after-image of the sun. Doubtless the painter strove to give the impression which one has on gazing at the sun. Whether or not this attempt was successful does not matter but it was gratifying to see the attempt made. There are many interesting effects obtainable by judicious experimentation. For example, if a gray medium be sprayed upon a landscape in such a manner that the material dries in a very rough or diffusing surface some remarkable effects of fog and haze may be produced. While experimenting in this manner a very finely etched clear glass was placed over a landscape and the combined effect of diffusely reflected light and of the slight blurring was remarkable. By separating the etched glass from the painting a slight distance, a very good imitation "porcelain" was produced. The optical properties of varnishes vary and their effect varies considerably, depending upon the mode of application. These and many other details are available to the painter and decorator. An interesting example among many is a cellulose lacquer dyed with an ordinary yellow dye. The solution appears yellow by transmitted light or it will color a surface yellow. By spraying this solution on a metallic object such as a nickel-plated piece, in a manner that leaves the medium rough or diffusing, the effect is no longer merely a yellow but a remarkable lustre resembling gilt. Quite in the same manner many effects of richness, depth of color, haziness, etc., are obtainable by the artist who is striving to produce a great illusion.