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this means sodium manganate is formed, which colours the bead bright green.

(6) Heat a small portion of metallic lead on a piece of charcoal in the oxidizing blow-pipe flame. Observe the yellow incrustation on the charcoal produced by the oxidation of the lead to litharge (PbO).

55. Blow-pipe reactions for the commonly occurring metals. *

(a) Compounds reduced to metal when heated with NaHCO3 on charcoal in reducing flame :

Antimony. Malleable beads. (6) Compounds reduced to metal when heated with a mixture of KCN and NaHCO, in reducing flame :

Copper.

Silver.

Lead.

Bismuth.

Brittle beads.

Tin.
White.

Red.

(c) Compounds reduced to metal when heated on charcoal with reducing agents, but which at once volatilize : Mercury.

Arsenic. (d) Compounds reduced to magnetic metallic powders when heated on charcoal with reducing agents : Iron. Nickel.

Cobalt, (e) Compounds reduced to metal when heated on charcoal with reducing agents, but which are at once converted into oxides :

Cadmium.

Zinc
Oxide is white.

Oxide is brown,

* These reactions must be carried out in the order indicated if they are applied to the examination of an unknown compound, since a metallic salt which is reduced by NaHCO3 alone, is reduced a fortiori by a mixture of KCN and NaHCO3.

(9) Compounds which, after being heated on char. coal, then moistened with CoCl2, and heated again, yield characteristic colours : Zinc. Aluminium.

Magnesium.

Green.

Blue.

Pink.

(8) Compounds which when fused in a borax bead impart to it a characteristic colour : Iron. Cobalt. Nickel. Manganese. Chromium. Copper. Yellow. Blue. Reddish Amethyst. Green. Blue.

yellow. (h) Compounds which impart a characteristic colour to any non-luminous flame : Barium. Strontium. Calcium. Potassium Sodium. Green, Crimson.

Red.
Violet.

Yellow. 56. Having found out approximately by these reactions what the substance is, proceed to apply the following

Confirmatory Tests. (a*) Silver bead soluble in HNO3. Solution yields with HCl white curdy precipitate of AgCl.

Lead bead soluble in HNO3. Solution yields with H.SO, heavy white precipitate of PbSO4 Bismuth bead soluble in HNO3. Solution

evaporated with HCl yields with H,S black precipitate of Bi2S3. Antimony bead soluble in HNO3. Solution

evaporated with HCl yields with H2S orange precipitate of Sb,Sz.

(6) Tin bead soluble in HNO3. Solution on evaporation yields white precipitate of SnO2.

* The letters correspond with those in the preceding paragraphs.

Copper bead soluble in HNO3. Solution, on addition of (NH4)HO in excess, yields deep blue solution.

(c) Mercury compounds, when heated in a small bulbtube with NaHCO3, yield the metal in minute globules.

Arsenic compounds, when heated in a small bulbtube with KCN + NaHCO, yield the metal as a shining mirror.

(d) Iron powder soluble in HNO3 + HCl yields yellow solution which gives a deep blue coloration with K Fe(CN)6

Cobalt powder soluble in HNO3 yields red solution, which gives a blue bead when fused with borax.

Nickel powder soluble in HNO3 yields green solution, which gives a reddish yellow bead when fused with borax.

(e) Cadmium oxide distinguished by its brown colour on the charcoal.

Zinc oxide distinguished by its yellow colour while hot, turning white when cold. (See also under f.)

(f) Zinc compounds, a green residue on charcoal when moistened with CoCl2 and re-heated. (See also under e.) Aluminium compounds, a blue residue

Best seen on charcoal when moistened with Coci,

when cold. and re-heated.

Magnesium compounds, a pink residue on charcoal when moistened with CoCl2 and re-heated.

(8) Iron borax bead, reddish yellow when hot, pale yellow on cooling in oxidizing flame.

Iron borax bead, light green in reducing flame.

Cobalt borax bead, deep blue in either oxidizing or reducing flame.

Nickel borax bead, reddish yellow when hot, paler on cooling, and finally nearly colourless in oxidizing flame.

Nickel borax bead, grey when heated in the reducing flame.

Manganese borax bead, amethyst-coloured in reducing flame, colour disappears in oxidizing flame.

Chromium borax bead, green in either oxidizing or reducing flame.

Copper borax bead, blue or greenish-blue in the oxidizing flame, becomes colourless in the reducing flame. (See also under b.)

(h) Barium salts colour the non-luminous gas flame pale green. Strontium salts colour the non-luminous

Best gas flame bright crimson.

after Calcium salts colour the non-luminous

moistening gas flame dull red.

the salt Potassium salts colour the non-luminous

with HCl. gas flame violet.

Sodium salts colour the non-luminous gas flame yellow.

seen

BUNSEN'S FLAME REACTIONS.

67.—The flame of an ordinary Bunsen lamp serves for nearly all the reactions which can be performed by the mouth blow-pipe. It is most convenient to use a lamp in which the admission of air can be regulated, and in which the flame is kept steady by a conical chimney supported from the tube of the lamp (see Fig. 15). Adjust the brass cap covering the holes dd,

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Fig. 13, so as to obtain a small luminous point at n, Fig. 15, and then notice the following zones of flame, and the purposes to which they are best suited.

a. Temperature low. Suitable for observing flame colorations of volatile substances. B. Highest temperature.

Suitable for fusions at high temperatures.

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