As to the colouring which may be given to bronze, and which is obtained by various methods of oxidation, the following are some of the methods in vogue: -

(1) The dull colour of medal bronze is obtained by rubbing with a mixture of red ochre and black lead applied by a brush.

(2) The antique green is obtained by washing the metal in a liquid made of 10 gr. marine salt, the same quantity of cream of tartar and acetate of copper, the whole dissolved in 200 gr. vinegar and 30 gr. carbonate of soda.

(3) The Florentine is obtained by means of green vitriol (sulphate of iron), and then rubbing with wax.

(4) The citron tint is obtained by means of red ochre mixed with lampblack and oil.

(5) The old green bronze is obtained by several dippings in acid, and subsequently with wax.

(6) Verdigris is obtained by means of sal-ammoniac, and wax afterwards.

(7) The smoke-tint is produced by annealing the object in a wisp of hay or straw, which is set on fire, and the article is burnished so that the oxide formed may penetrate the metal. The smoke of turf may be used instead, waxing afterwards, and removing the grease by turpentine so as to carry off the uneven first layer.

(8) Dark or Berlin Bronze. Cleanse the metal by dipping it first momentarily in nitric acid, then rinsing quickly in running water, and rubbing with sawdust. The bronzing dip may be prepared by dissolving in 1 gal. hot water 1/2 lb. each perchloride of iron and perchloride of copper. The metal should not be allowed to remain in this dip any longer than is necessary to produce the desired colour. Rinse well, dry, and polish in warm sawdust or with a rag buff.

(9) In preparing bronze medals for the Melbourne Exhibition, a rich chocolate colour was obtained by the addition of a little copper acetate, mixed with an alkaline sulphide, to the ordinary colcothar bronzing powder, by which a film of mixed copper sulphide and oxide, somewhat resembling Chinese bronze, was produced.