Thebead test is a traditional part ofqualitative inorganic analysis to test for the presence of certain metals. The oldest one is theborax bead test orblister test. It was introduced byBerzelius in 1812.^[1] Since then other salts were used asfluxing agents, such assodium carbonate orsodium fluoride. The most important one after borax ismicrocosmic salt,^[1] which is the basis of themicrocosmic salt bead test.^[2]

A small loop is made in the end of aplatinum wire and heated in a Bunsen burner flame until red hot. A stick made of another inert substance such as a magnesia stick (MgO) may also be used.It is then dipped into powderedborax and held in the hottest part of the flame where it swells up as it loses itswater of crystallization and then shrinks, forming a colourless, transparent glass-like bead (a mixture ofsodium metaborate andboric anhydride).

The bead is allowed to cool and then wetted and dipped into the sample to be tested such that only a tiny amount of the substance adheres to the bead. If too much substance is used, the bead will become dark and opaque. The bead and adhering substance is then heated in the lower,reducing, part of the flame, allowed to cool, and the colour observed. It is then heated in the upper,oxidizing, part of the flame, allowed to cool, and the colour observed again.^[2]

Characteristic coloured beads are produced with salts ofcopper,iron,chromium,manganese,cobalt andnickel. After the test, the bead is removed by heating it to fusion point, and plunging it into a vessel of water.

• Flame test

• Chemical tests

• Articles with short description
• Short description is different from Wikidata