calf-bound books, tanned presumably with oak bark. The new form
affects nearly all leathers, and in extreme cases seems absolutely to
destroy the fibres. Another form of deterioration, more noticeable in
the newer books, renders the grain of the leather liable to peel off
when exposed to the slightest friction. This is the most common form
of decay noted in the more recent leathers. In nearly all samples of
Russia leather a very violent form of red decay was noticed. In many
cases the leather was found to be absolutely rotten in all parts
exposed to light and air, so that on the very slightest rubbing with a
blunt instrument the leather fell into fine dust....

"The second point is the cause of the decay. An extensive series of
experiments was carried out with a view of determining the causes of
the decay of bindings. The sub-committee find that this is caused by
both mechanical and by chemical influences. Of the latter, some are
due to mistakes of the leather manufacturer and the bookbinder, others
to the want of ventilation, and to improper heating and lighting of
libraries. In some cases inferior leathers are finished (by methods in
themselves injurious) so as to imitate the better class leathers, and
of course where these are used durability cannot be expected. But in
the main the injury for which the manufacturer and bookbinder are
responsible must be attributed rather to ignorance of the effect of
the means employed to give the leather the outward qualities required
for binding, than to the intentional production of an inferior
article.... Leathers produced by different tanning materials, although
they may be equally sound and durable mechanically, vary very much in
their resistance to other influences, such as light, heat, and gas
fumes.

"For bookbinding purposes, the sub-committee generally condemn the use
of tanning materials belonging to the catechol group, although the
leathers produced by the use of these materials are for many purposes
excellent, and indeed superior. The class of tanning materials which
produce the most suitable leather for this particular purpose belong
to the pyrogallol group, of which a well known and important example
is sumach. East Indian or 'Persian' tanned sheep and goat skins, which
are suitable for many purposes, and are now used largely for cheap
bookbinding purposes, are considered extremely bad. Books bound in
these materials have been found to show signs of decay in less t