1) Yellow antimony. This corresponds to white phosphorus and yellow arsenic: it is transparent and solubile in CS2, and is evidently covalent. It was
prepared by Stock(*) by the action of oxygen on liquid stibine SbH3 at -90 C. It is very unstable. It changes in light at -180, and even in the dark
at -90, into the second form:
2) Black antimony. This is formed from the yellow form, or by the action of oxygen on liquid stibine SbH3 at low temperatures but above -80 C, or by
the rapid cooling of antimony vapour. It is much more chemically active than the ordinary form: it is oxidized by cold air, and is sometimes
pyrophoric. On heating it transforms into the metallic form.
(*) Stock & Guttmann Ber 1904, 37, 885.
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