This is another of the primary colors and a very essential one, it being the nearest allied to shade, and although not shade itself, no shadows can be produced without it. We will find it, therefore, mingling with all the shades of nature between the lights and shadows. It would be in vain for us to introduce all our warm colors, if the cool tints that are produced by blue are wanting; for, without that, the work will appear heavy, as it is the contrast between blue and the warm colors that produces a balance of color. Blue mixed with yellow makes a very brilliant green, with gold a duller green, with magenta a purple. In landscapes it is used in skies and the middle distances, but not in the foreground, unless mixed with yellow. Blue can be mixed with rose or magenta for sunset skies. When the horizon is represented a streak of blue or rose, or of blue and magenta, will give a very pleasing effect. In portraits if you have a light background, a thin wash of blue can be used over it. The same can also be used for blue eyes and for dresses when they are light in the picture, also in all the half-shadows of the dresses or draperies without regard to what their other color may be.