The principles connected with coloring should be understood if one desires to produce the most pleasing and harmonious effects in painting. The three colors, red, yellow, and blue, with the white of the paper, are equal in theory to all the requirements of art in its true relation to color. Red, yellow and blue are called primary colors; that is, we cannot produce these colors from the combination of any others. Orange, purple and green are called secondary colors, and are produced by the combination of the primary colors. By the mixture of red and yellow we obtain orange, from red and blue, purple, from yellow and blue, green. The tertiary colors—broken green, gray and brown—are produced by the mixture of the secondary colors. From orange and purple we obtain brown, from orange and green, broken green, and from purple and green, gray. The three primary colors must always be present in a picture to produce harmony. Colors are divided into what are called warm and cold colors, the yellow and red being termed warm, and the blue cold. Yellow and red produce light and warmth, and it is impossible to produce coolness without the use of blue. In painting we use the three terms, light, shade and color, because they best express the qualities of color. Light is expressed by yellow, shade by blue, and color by red. While red is particularly designated as color, we must not forget the claims of yellow and blue, as they, together with red, complete the primary scale of colors. It is by placing these different colors in juxtaposition that we produce the proper qualities existing in each of the other colors. It is impossible to produce the effect of warmth by red and yellow unless we use the blue in connection with them. It is this filling up, or completing the primary scale of colors, that gives the term complementary, so often employed in speaking of colors. Thus red is said to be complementary to green, as green contains the other two colors of the primary scale—blue and yellow. Blue is complementary to orange, as orange contains red and yellow. Yellow is complementary to purple, as purple contains blue and red. The principle of using the complementary color is of the utmost importance in painting, or the use of color by any method, and it is on this principle that the harmony of color is based. When a painting is produced that has the colors red, yellow and blue properly balanced, a pleasing and harmonious effect is attained; but if these colors are not used in their proper relations, there is a discord, and the work is not satisfactory. These rules must be borne in mind by every student in coloring, whether he uses oil or water colors. One of the most common errors of amateurs is to overlook the red in landscape. Thus trees are too green, and the grass is insufferably green: the complementary color, red, has been left out.

By the following experiment you may prove that when you see one color the eye is in a perfect condition to see its complementary color. On a piece of white paper, three inches wide and five inches long, draw with a lead pencil an oblong, half an inch from the top, one inch wide, and two and one-half inches long from right to left, and a similar oblong one-half an inch below the one already drawn. Then draw a six pointed star (or any other not too large figure you desire) in the centre of the upper oblong, and paint it with vermilion water color. Now look intently at the painted star for thirty seconds, and then look at the plain oblong below, and you will observe that the latter will gradually assume a very beautiful shade of green, the exact complementary color of the vermilion, with the figure in white upon it—unless you should happen to be color blind. If that is the case, the experiment will demonstrate that fact.