f this mixture, suitable for small library purposes, can be made by
boiling half an ounce (by weight) of the stearic acid, and one-sixteenth
of an ounce (by weight) of the caustic soda, in three liquid ounces of
water and then adding nine liquid ounces of cold water. It is best to stir
the mixture gently while cooling; the entire process of preparation will
take only a few minutes. If kept for more than a week or two, this
mixture may become mouldy. It is better to prepare it only when it can be
used on a number of books at once.

Books in closed cases should be removed and thoroughly dusted at least
once a year, the tops especially being carefully wiped clean, if gilt, or
brushed, if uncut, in either case while holding the book tightly closed.
They should be aired at the same time, particularly those not in frequent
use. For this airing and cleaning a warm, sunny day should be selected
and, whenever possible, on such days the cases should be opened; books,
like people, are healthier when well supplied with good, fresh air.

Books on the shelves should set in firmly among their neighbors, as a
certain amount of pressure on the sides is essential to keep the boards
from warping. Care must be taken, however, not to wedge them in too
tightly; such a cure is worse in its effects than the disease. The usual
method of removing a book from the shelf is to hook a finger into the top
of the back, or head-cap, and pull. Paper or cloth backs are often torn at
the top in this way. It is far preferable to reach in with the hand and
push the book out from the fore-edge or, at least, to tilt it outward by a
slight pressure of several fingers on the top beyond the head-band. If the
shelves are lined with velvet, as elsewhere suggested, it will be
necessary to lift the heavier books into place when returning them to the
shelves; if they are shoved in on the lower edges of the boards the velvet
will follow them in.

Books in delicate bindings or fragile covers may often, with advantage, be
fitted with slip-covers of silk, cloth, Japan vellum, or even soft, heavy
paper. These covers are simple and easy to make, but they can be used only
when the condition of the book will permit both boards to bend backward
without injury, while slipping the cover on or off. (Fig. A.) Covers of
this kind, made of leather and provided with a label on the back, are
especially adaptable to paper-covered books which, for any reason, one may
wish to preserve