The extract of walnut-shells and chromate of potash are procurable at any large druggist’s establishment.  A dark-brown is the result of the action of copper salts on the yellow prussiate of potash; the sulphate of copper in soft woods gives a pretty reddish-brown colour, in streaks and shades, and becomes very rich after polishing or varnishing.  Different solutions penetrate with different degrees of facility.  In applying, for instance, acetate of copper and prussiate of potash to larch, the sap-wood is coloured most when the acetate is introduced first; but when the prussiate is first introduced, the heart-wood is the most deeply coloured.  Pyrolignite of iron causes a dark-grey colour in beech, from the action and tannin in the wood on the oxide of iron; while in larch it merely darkens the natural colour.  Most of the tints, especially those caused by the prussiates of iron and copper, are improved by the exposure to light, and the richest colours are produced when the process is carried out rapidly.

=Imitation Ebony.=—­Take half a gallon of strong vinegar, one pound of extract of logwood, a quarter of a pound of copperas, two ounces of China blue, and one ounce of nut-gall.  Put these into an iron pot, and boil them over a slow fire till they are well dissolved.  When cool, the mixture is ready for use.  Add a gill of iron filings steeped in vinegar.  The above makes a perfect jet black, equal to the best black ebony.  A very good black is obtained by a solution of sulphate of copper and nitric acid; when dry, the work should have a coat of strong logwood stain.

=Imitation Oak.=—­To imitate old oak, the process known as “fumigating” is the best.  This is produced by two ounces of American potash and two ounces of pearlash mixed together in a vessel containing one quart of hot water.

Another method is by dissolving a lump of bichromate of potash in warm water; the tint can be varied by adding more water.  This is best done out of doors in a good light.  Very often in sending for bichromate of potash a mistake is made, and chromate of potash is procured instead; this is of a yellow colour, and will not answer the purpose.  The bichromate of potash is the most powerful, and is of a red colour.  A solution of asphaltum in spirits of turpentine is frequently used to darken new oak which is intended for painter’s varnish, or a coating of boiled oil.

Another method of imitating new oak upon any of the inferior light-coloured woods is to give the surface a coat of Stephens’s satin-wood stain, and to draw a soft graining-comb gently over it, and when the streaky appearance is thus produced a camel-hair pencil should be taken and the veins formed with white stain.  This is made by digesting three-quarters of an ounce of flake white (subnitrate of bismuth), and about an ounce of isinglass in two gills of boiling water; it can be made thinner by adding more water, or can be slightly tinted if desired.