>33. Having thus obtained the power of laying on a tolerably flat tint, you must try to lay on a gradated one. Prepare the color with three or four teaspoonfuls of water; then, when it is mixed, pour away about two-thirds of it, keeping a teaspoonful of pale color. Sloping your paper as before, draw two pencil lines all the way down, leaving a space between them of the width of a square on your chess-board. Begin at the top of your paper, between the lines; and having struck on the first brushful of color, and led it down a little, dip your brush deep in water, and mix up the color on the plate quickly with as much more water as the brush takes up at that one dip: then, with this paler color, lead the tint farther down. Dip in water again, mix the color again, and thus lead down the tint, always dipping in water once between each replenishing of the brush, and stirring the color on the plate well, but as quickly as you can. Go on until the color has become so pale that you cannot see it; then wash your brush thoroughly in water, and carry the wave down a little farther with that, and then absorb it with the dry brush, and leave it to dry.

34. If you get to the bottom of your paper before your color gets pale, you may either take longer paper, or begin, with the tint as it was when you left off, on another sheet; but be sure to exhaust it to pure whiteness at last. When all is quite dry, recommence at the top with another similar 22 mixture of color, and go down in the same way. Then again, and then again, and so continually until the color at the top of the paper is as dark as your cake of Prussian blue, and passes down into pure white paper at the end of your column, with a perfectly smooth gradation from one into the other.

35. You will find at first that the paper gets mottled or wavy, instead of evenly gradated; this is because at some places you have taken up m