Scraps of iron are placed in casks or other vessels, and covered with rectified raw pyroligneous acid. There are usually a series of vessels, through which the solution is successively passed till it is fully saturated.

[To produce good and permanent dyes, several successive processes are required, which cannot be described here. In domestic dyeing, for trifling articles, the dye and mordant are often boiled together, and the silk, etc, immersed in the liquid. The following are some examples: Crimson. - Boil 1 oz. Brazil-wood, with 1 dr. of alum and 1/2 dr. of cream of tartar in a quart of water. Purple, or Lilac. - Archil 1 oz. (or cudbear 1 oz.), pearlash 1 dr., hot water a quart. Rose, or Flesh Colour. - Pink saucers, with a little lemon-juice, will be found convenient. Violet. - Boil 4 oz. of logwood with 1 oz. alum and 1/4 oz of tartar in a quart of water. Blue. - Add to the water as much sulphate of indigo (chemic blue) as will give it the required colour. Or one of the other solutions of indigo (see back) may be used. Yellow. - Boil 2 oz. of turmeric, or 4 oz. quercitron, or a drachm of saffron, with 1/2 oz of alum, in a quart of water. Green. - Add to the yellow dye, sufficient chemic blue to render it green. Rose-red, for silk. - Put your silk into a hot solution of alum and tartar; then into a hot decoction of madder. Scarlet, for silk. - Dye it yellow with saffron and alum; then put it into a decoction of cochineal and madder. Black. - Boil 1 oz of logwood, 1/4 oz. sumach, and 1 dr. of copperas, in 4 pints of water. Buff. - Boil 1 oz. of fustic, 1 dr. of alum, in 4 pints of water.]