1624. Colors may thus be fixed, which otherwise become pale, or nearly white.
1625. Some plants require more moderate heat than others, and herein consists the nicety of the experiment; but I have generally found, that if the iron be not too hot, and is passed rapidly, yet carefully, over the surface of the blotting-paper, it answers the purpose equally well with plants of almost every variety of hue and thickness.
1626. In compound flowers, with those also of a stubborn and solid form as the Centaurea, some little art is required in cutting away the under part, by which means the profile and forms of the flowers will be more distinctly exhibited.
1627. This is especially necessary, when the method employed by Major Velley is adopted: viz., to fix the flowers and fructification down with gum upon the paper previous to ironing, by which means they become almost incorporated with the surface.
1628. When this very delicate process is attempted, blotting-paper should be laid under every part excepting the blossoms, in order to prevent staining the white paper. Great care must be taken to keep preserved specimens in a dry place.