This sodium reaction is extremely delicate, it being possible to detect with ease a quantity of a sodium salt less than 1/3000000 of a milligram in weight.
Potassium colors the flame purplish-violet.
Barium colors the flame apple-green.
Strontium colors the flame crimson.
Calcium colors the flame orange-red, distinguished from strontium, by appearing gray when seen through blue glass.
Boracic acid colors the flame green when the substance has been moistened with glycerine.
Examination in Borax Bead.—Borax, Na2B4O7, and microcosmic salt,
NaNH4H . PO4,
possess the property of dissolving many of the metallic oxides at the temperature of the Bunsen flame.
For example, with oxide of cobalt, the following reactions take place with the two fluxes:—