Microcosmic salt bead tests

Phosphate (or microcosmic salt) bead tests The bead is produced similarly to the borax head except that microcosmic salt, sodium ammonium hydrogen phosphate tetrahydrate Na(NH4)HP04.4H20, is used. The colourless, transparent bead contains sodium metaphosphate ... 

Unless silicates are removed here, they are likely to be confused with Al(OH)3 in the group separation. Repeated evaporation with concentrated HC1 converts silicates into a granular form of hydrated silica, which is readily filtered, particularly after a final digestion with dilute HC1. The precipitate should be subjected to the microcosmic salt bead test or to the silicon tetrafluoride test (Section IV.26). 

Microcosmic salt bead test reducing flame, cold - blue blood-red when fused with a trace of iron(II) sulphate. 

Results obtainable with the borax-bead test are summarized in Table 2.4. In certain circumstances the borax-bead test is inconclusive, but it can be supplemented with the phosphate (or microcosmic salt) bead test (see below). 

Dry test Microcosmic salt bead oxidizing flame - colourless or pale-yellow reducing flame - blue, changing to blood-red upon the addition of a little iron(II) sulphate. 

Dry tests a. Microcosmic salt bead oxidizing flame - yellow to green while hot and colourless when cold reducing flame - brown when hot, green when cold. 

Dry test 11. Dry test microcosmic salt bead oxidizing flame colourless or pale-... 

Dry test microcosmic salt bead oxidizing flame colourless reducing flame - yellow whilst hot and violet when cold (this result is obtained more rapidly if a little tin(II) chloride is added). If the bead is heated in the reducing flame with a trace of iron(II) sulphate, it acquires a blood-red colour. 

A qualitative test for HO2 is a blue-violet coloration of beads of microcosmic salt (NaNH4HP04 4H20),ora yeUow-orange coloration produced when hydrogen peroxide is added to a test solution in hot, concentrated sulfuric acid containing ammonium... 

Bead test procedure. Make a loop in the end of a platinum wire. Heat the Pt-wire to redness and then dip it into borax or microcosmic salt powder. A small amount of salt is coated... 

Table 12.14. Bead test made with microcosmic salt (NaNH,HPO,)...

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