But a marbled edge presents a far more handsome appearance, and should harmonize in color and figure with the marbled paper of the end leaves. Marbling, so called from its imitation of richly veined colored marble, is staining paper or book edges with variegated colors. The process of marbling is highly curious, both chemically and aesthetically, and may be briefly described. A large shallow trough or vat is filled with prepared gum water (gum-tragacanth being used); on the surface of this gum-water bright colors, mixed with a little ox-gall, to be used in producing the composite effect aimed at in the marbling are thrown or sprinkled in liquid form. Then they are deftly stirred or agitated on the surface of the water, with an implement shaped to produce a certain pattern. The most commonly used one is a long metallic comb, which is drawn across the surface of the combined liquids, leaving its pattern impressed upon the ductile fluid. The edges of the book to be marbled are then touched or dipped on the top of the water, on which the coloring matter floats, and at once withdrawn, exhibiting on the edge the precise pattern of "combed marble" desired, since the various colors--red, yellow, blue, white, etc., have adhered to the surface of the book-edges. The serrated and diversified effect of most comb-marbling is due to stroking the comb in waved lines over the surface. The spotted effect so much admired in other forms, is produced by throwing the colors on with a brush, at the fancy of the skilled workman, or artist, as you may call him. Marbled paper is made in the same way, by dipping one surface of the white sheet, held in a curved form, with great care on the surface of the coloring vat. This is termed shell and wave marbling, as distinguished from comb-marbling. The paper or the book edges are next finished by sizing and burnishing, which gives them a bright glistening appearance. A still more ornate effect in a book is attained by gilding the edges. Frequently the head of a book is gilt, leaving the front and tail of an uncut book without ornament, and this is esteemed a very elegant style by book connoisseurs, who are, or should be solicitous of wide margins. The gilding of the top edge is a partial protection from dust falling inside, to which the other edges are not so liable. To gild a book edge, it is placed in a press, the edges scraped or smoothed, and coated with a red-colored fluid, which serves to heighten the effect of the gold. Then a sizing is applied by a camel's-hair brush, being a sticky substance, usually the white of an egg, mixed with water (termed by binders "glaire") and the gold-leaf is laid smoothly over it. When the sizing is dry, the gold is burnished with a tool, tipped with an agate or blood-stone, drawn forcibly over the edge until it assumes a glistening appearance.