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 gra.s.s 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 or filtered and warm or only tepid, for fear of injuring the surface of the ivory. Increasing the temperature also sometimes deepens or changes the colour. The best temperature is 100 deg. Fahr.

When sufficiently stained the ivory is well rinsed in water, and if there are two colours on top of each other always well rinsed before going into the second bath. After thoroughly drying, repolish by friction, first with a few drops of oil on a soft clean rag; continue with a dry clean rag till the oil disappears.

An old Italian receipt for polishing wood blackened to imitate ebony runs thus:--"Is the wood to be polished with burnt pumice stone? Rub the work carefully with canvas and this powder, then wash the piece with Dutch lime water so that it may be more beautifully polished. Then it is to be cleaned with another cloth. Then the rind of a pomegranate must be steeped, and the wood smeared over with it and set to dry, but in the shade."