anned with sumach or some closely allied
tanning material. Morocco bindings earlier than 1860 were generally
found to be in fairly good condition, but morocco after that date
seems to be much less reliable, and in many cases has become utterly
rotten. During the latter part of the 18th century it became customary
to pare down calf until it was as thin as paper. Since about 1830
hardly any really sound calf seems to have been used, as, whether
thick or thin, it appears generally to have perished. Sheepskin
bindings of the early part of the century are many of them still in
good condition. Since about 1860 sheepskin as sheepskin is hardly to
be found. Sheepskins are grained in imitation of other leathers, and
these imitation-grained leathers are generally found to be in a worse
condition than any of the other bindings, except, perhaps, some of the
very thin calfskin. Undyed modern pigskin seems to last well, but some
coloured pigskin bindings had entirely perished. Modern leathers dyed
with the aid of sulphuric acid are all to be condemned. In nearly
every case Russia leather was found to have become rotten, at least in
bindings of the last fifty years."

On the question of the causes of the decay noticed and the best
methods of preparing leather in the future, I may quote the
following:--

"The work of a sub-committee, which was composed of chemists specially
conversant with the treatment of leather, was directed specially to
the elucidation of the following points: an investigation of the
nature of the decay of leather used for bookbinding; an examination of
the causes which produced this decay; a research into the best
methods of preparing leather for bookbinding; and a consideration of
the points required to be dealt with in the preservation of books.

"Taking these points in order, the first one dealt with is the
question of the nature of the decay of leather. To arrive at their
conclusions on this subject, the sub-committee made a number of tests
and analyses of samples of decayed leather bookbindings, as well as of
leathers used for binding. The committee found that the most prevalent
decay was what they term a red decay, and this they think may be
differentiated into old and new, the old red decay being noticeable up
to about 1830, and the new decay since that date. In the old decay,
the leather becomes hard and brittle, the surface not being easily
abraded by friction. The older form is specially noticeable in