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at once withdrawn, exhibiting on the edge the precise pattern of "combed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.

After the edges have been treated by whatever process, there follows what
is termed the "backing" of the book. The volume is pressed between iron
clamps, and the back is hammered or rolled where it joins the sides, so
as to form a groove to hold the boards forming the solid portion of the
cover of every book. A backing-machine is sometimes used for this
process, making by pressure the joint or groove for the boards.