Saltpeter, heat.
Copper sulphate and ammonium chloride, heat.
Silver nitrate, sunlight.
Gold trichloride, sunlight.
Ferric sulphate, infusion of gallnuts or ferrocyanide of potassium.
Copper sulphate, ferrocyanide of potassium.
Lead vinegar, hydrogen sulphide.
Mercuric nitrate, hydrogen sulphide.
Starch water, tincture of iodine or iodine vapors.
Cobalt nitrate, oxalic acid.