and immediate washing gives a duller and deeper red
than the first red-cloth stain. The depth of colour may be increased by
longer immersion _or_ a higher temperature. A dull scarlet or brick red
is made by the Brazil bath, followed by thirty to sixty minutes in an
alum mordant.

The cloth stain for one hour, followed by pearl ash for half-an-hour,
gives a bright purple; if iron is used instead of pearl ash a sombre
purple results; if you add alkalies to the stain instead of sulphuric
acid you obtain purple reds. Fifteen minutes in Brazil, and then three
or four in pearl ash gives full red purples deepening to maroon. Five
minutes in logwood water stain gives a good warm brown; half-an-hour, a
chocolate brown. Ten minutes in logwood stain, washing, and one or two
seconds in pearl ash, and instantly washing again gives a deep red
brown, and if one minute in alum instead of pearl ash a deep purple
brown.

Blue stains may be made from sulphate of indigo, 1/2 drachm to 1 pint of
previously boiled water, with 10 grains of carbonate of potash added.
One to two minutes' immersion and immediate washing yields a delicate
turquoise, five minutes a bright full blue; and ten to fifteen a
considerable depth of colour. Blues are rather fugitive. Staining with
saffron or fustic for five minutes, and then with indigo for the same
time, produces a clear pea green; with indigo for ten minutes, a deep
grass green. The greens from fustic are more permanent and yellower. The
sequence of the stains also affects the green, the last used having most
effect. Blue stain first for fifteen minutes, followed by fustic for
thirty, stains ivory the green used for table knife handles--a colour
which may also be obtained by immersion for some weeks in a clear
solution of verdigris in dilute vinegar and water.

Before applying these stains the ivory must be prepared by first
polishing with whiting and water and washing quite clean. Next immerse
it for three to five minutes in acid cold water (1 part muriatic acid to
40 or 50 of water, or the same proportion of nitric). This extracts the
gelatine from the surface of the ivory. Extreme cleanliness and absence
of grease or soiling is most important; the ivory is not to be touched
by the fingers, but removed from one vessel to another by wooden tongs,
one pair to each colour. After treating with the acid, place the ivory
in clean, cold, boiled water for some minutes. Water stains are used,
but strained o