, only a few
sheets at the beginning or end of the book have to be washed, it will
be necessary to tone down the washed sheets to match the rest of the
book by putting some stain in the size. For staining there are many
things used. A weak solution of permanganate of potash gives a
yellowish stain that will be found to match many papers. Other stains
are used, such as coffee, chicory, tea, liquorice, &c. Whatever is
used should be put in the size. To ascertain that the right depth of
colour has been obtained, a piece of unsized paper, such as white
blotting-paper, is dipped in the stained size and blotted off and
dried before the fire. It is impossible to judge of the depth of
colour in a stain unless the test piece is thoroughly dried. If the
stain is not right, add more water or more stain as is needed.
Experience will tell what stain to use to match the paper of any given
book.

To remove grease or oil stains, ether may be used. Pour it freely in a
circle round the spot, narrowing the circle gradually until the stain
is covered. Then apply a warm iron through a piece of blotting-paper.

Ether should only be used in a draught in a well-ventilated room on
account of its well-known inflammable and anaesthetical properties.

A very dilute (about one per cent.) solution of pure hydrochloric acid
in cold water will be found to take out some stains if the paper is
left in it for some hours. When the paper is removed from the
solution, it must be thoroughly washed in running water. It is
important that the hydrochloric acid used should be pure, as the
commercial quality (spirits of salts) often contains sulphuric acid.

The following recipes are quoted from _De l'organisation et de
l'administration des Bibliotheques, par Jules Cusin_:--

To remove stains from paper:--"_Mud Stains._--To take away these kinds
of stains, spread some soap jelly very evenly over the stained places,
and leave it there for thirty or forty minutes, according to the depth
of the stain. Then dip the sheet in clean water, and then having
spread it on a perfectly clean table, remove the soap lightly with a
hog's hair brush or a fine sponge; all the mud will disappear at the
same time. Put the sheet into the clear water again, to get rid of the
last trace of soap. Let it drain a little, press it lightly between
two sheets of blotting-paper, and finish by letting it dry slowly in
a dry place in the shade.

"_Stains of Tallow, Stearine, or Fat._--To