Bead test
The bead test is a traditional part of
Borax bead
A small loop is made in the end of a platinum 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 powdered
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,
Characteristic coloured beads are produced with salts of copper, iron, chromium, manganese, cobalt and nickel. After the test, the bead is removed by heating it to fusion point, and plunging it into a vessel of water.
Metal[3] | Oxidizing flame |
Reducing flame[4]
|
---|---|---|
Aluminum |
colorless (hot and cold), opaque | colorless, opaque |
Antimony | colorless, yellow or brown (hot) | gray and opaque |
Barium | colorless | |
Bismuth | colorless, yellow or brownish (hot) | gray and opaque |
Cadmium | colorless | gray and opaque |
Calcium | colorless | |
Cerium | red (hot) | colorless (hot and cold) |
Copper | sky blue (hot and cold), opaque | red, opaque |
Iron | yellow (hot and cold), opaque | bottle-green, opaque |
Manganese | pink (hot and cold), opaque | colorless, opaque |
Cobalt | deep blue (hot and cold), opaque | deep blue, opaque |
Nickel | yellow-brown (hot and cold), opaque | grey, opaque |
Silver | colourless (hot and cold), opaque | grey, opaque |
Vanadium | colourless(hot and cold), opaque | green, opaque |
Uranium | yellow-brown (hot and cold), opaque | green, opaque |
Chromium | green (hot and cold), opaque | green, opaque |
Platinum | colourless(hot and cold), opaque | grey, opaque |
Gold | yellow-brown (hot and cold), opaque | grey, opaque |
Tin | colourless(hot and cold), opaque | colourless, opaque |
Titanium | colourless (hot and cold), opaque | yellow, opaque (hot) violet (cold) |
Tungsten | colourless(hot and cold), opaque | brown, opaque |
Magnesium | colourless(hot and cold), opaque | colourless, opaque |
Molybdenum | colourless(hot and cold), opaque | yellow or brown, opaque |
Strontium | colourless(hot and cold), opaque | colourless, opaque |
Thorium | colourless(hot and cold), opaque | colourless, opaque |
Yttrium | colourless(hot and cold), opaque | colourless, opaque |
Neodymium | colourless(hot and cold), opaque | colourless, opaque |
Praseodymium | colourless(hot and cold), opaque | colourless, opaque |
Silicon | colourless(hot and cold), opaque | colourless, opaque |
Germanium | colourless(hot and cold), opaque | colourless, opaque |
See also
References
- ^ a b Materials Handbook: A Concise Desktop Reference, François Cardarelli [1]
- ^ ISBN 0-582-44367-9 – via the Internet Archive
- ISBN 0-8493-0466-0.
- ^ "Borax Bead Tests".