ecial irons must be cut, using the tooling still
in place as a guide. With patience and skill, one may fashion these for
himself. The required ornamentation is traced from another spot where it
is still intact on the binding, with a brush holding resin varnish or wax.
This tracing, which naturally leaves an imprint in reverse, is applied to
a piece of copper, and the design retouched on the copper with the same
varnish or wax.[25] The other faces of the cube or cylinder of copper used
are coated, and the copper placed in a bath of azotic acid. The acid will
eat the metal not protected as above, leaving the ornament standing out in
relief, something after the manner of a stereotype plate. Or, the
electro-chemical procedure of stereotyping may be used to the same end.

By the aid of a form obtained in some such manner as the above, it is
possible to restore the effaced ornaments, provided that the leather is
prepared to receive and hold the gold. Let me note in passing that it is
difficult for inexperienced amateurs to set gold smoothly; only long
practice will make this possible. Necessarily, the very thin gold leaf
always covers and reaches beyond the spot to be tooled. It is essential
that the iron be pressed exactly upon the spot intended to receive it,
which is very difficult to accomplish. Moreover, the gold must be kept
smooth and fresh over the entire impression. Perhaps one might substitute
for the gold leaf a coat of gold powder spread over the design, which
should be coated with albuminous paste (glaire) to hold the powder.

One sometimes wishes, also, to rectify a defective title or erroneous date
on the binding. The simplest method is to stamp the desired lettering or
date on an odd bit of leather, which is then applied to the book. The
amateur may do this himself if he has the necessary letter, a form to
hold them, and a certain amount of skill.

Suppose a case where, in a title anciently gilt and which one wishes to
preserve, there is a single letter or a single character to change. It is
first necessary to efface the letter or character to be replaced. To do
this, it is touched with a drop of alcohol; on wiping it, the varnish
which may have covered the gold is removed. If the gold resists thorough
rubbing, chemical compositions may be tried. I would not advise, however,
the use of aqua-regia, the infallible dissolvent of gold, because it would
disorganize the leather. I think that a drop of mercury, appli