harden leather than to keep it flexible, and they fail just
where failure is most serious, that is at the joints. In opening and
shutting, any coat of glair or varnish that has become hard will
crack, and expose the leather of the joint and back. Flexibility is an
essential quality in bookbinding leather, for as soon as the leather
at the joint of a binding becomes stiff it breaks away when the boards
are opened.

It would add immensely to the life of old leather bindings if
librarians would have them treated, say once a year, with some
preservative. The consequent expense would be saved many times over by
the reduction of the cost of rebinding. Such a preservative must not
stain, must not evaporate, must not become hard, and must not be
sticky. Vaseline has been recommended, and answers fairly well, but
will evaporate, although slowly. I have found that a solution of
paraffin wax in castor oil answers well. It is cheap and very simple
to prepare. To prepare it, some castor oil is put into an earthenware
jar, and about half its weight of paraffin wax shredded into it. On
warming, the wax will melt, and the preparation is ready for use.

A little of the preparation is well worked into a piece of flannel,
and the books rubbed with it, special attention being paid to the back
and joints. They may be further rubbed with the hand, and finally gone
over with a clean, soft cloth. Very little of the preparation need be
used on each book.

If bindings have projecting metal corners or clasps that are likely to
scratch the neighbouring books, pieces of mill-board, which may be
lined with leather or good paper, should be placed next them, or they
may have a cover made of a piece of mill-board bent round as shown at
fig. 120, and strengthened at the folds with linen. This may be
slipped into the shelf with the book with the open end outwards, and
will then hardly be seen.

[Illustration: FIG. 120.]

Bindings which have previously had metal clasps, &c., often have
projecting fragments of the old nails. These should be sought for and
carefully removed or driven in, as they may seriously damage any
bindings with which they come in contact.

To protect valuable old bindings, cases may be made and lettered on
the back with the title of the book.

Loose covers that necessitate the bending back of the boards for their
removal are not recommended.

RE-BACKING

Bindings that have broken joints