Reducing-flame sentence example

reducing-flame
  • Heat the substance on a piece of charcoal in the reducing flame of the blowpipe.
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  • If the bead is coloured we may have present: cobalt, blue to violet; copper, green, blue on cooling; in the reducing flame, red when cold; chromium, green, unaltered in the reducing flame; iron, brownish-red, light-yellow or colourless on cooling; in the reducing flame, red while hot, yellow on cooling, greenish when cold; nickel, reddish to brownish-red, yellow to reddish-yellow or colourless on cooling, unaltered in the reducing flame; bismuth, yellowish-brown, light-yellow or colourless on cooling; in the reducing flame, almost colourless, blackish-grey when cold; silver, light yellowish to opal, somewhat opaque when cold; whitish-grey in the reducing flame; manganese, amethyst red, colourless in the reducing flame.
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  • When mixed with sodium carbonate and heated on charcoal in the reducing flame lead salts yield malleable globules of metal and a yellow oxide-ring.
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  • Analysis.-A borax bead dissolves uranium oxides in the reducing flame with a green, in the oxidizing flame with a yellow, colour.
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  • In the reducing flame the bead becomes violet, more readily on the addition of tin; in the presence of iron it becomes blood-red.
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  • To obtain a good reducing flame (in which the combustible matter, very hot, but not yet burned, is disposed to take oxygen from any compound containing it), the nozzle, with smaller orifice, should just touch the flame at a point higher above the wick, and a somewhat weaker current of air should be blown.
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  • Antimony compounds when heated on charcoal with sodium carbonate in the reducing flame give brittle beads of metallic antimony, and a white incrustation of the oxide.
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  • Sulphates may be detected by heating the salt mixed with sodium carbonate on charcoal in the reducing flame of the blowpipe; sodium sulphide is thus formed, and may be identified by the black stain produced if the mass be transferred to a silver coin and then moistened.
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