The Elements of Blowpipe Analysis

by Frederick Hutton Getman

Illustrations. Examine some potassium nitrate, KNO₃, before the Bp. on Ch., also some ammonium nitrate, NH₄NO₃.

g. Intumescence.

Illustration. Examine some alum,

K₂Al₂(SO₄)₄,

before the Bp. on Ch.

h. Incandescence.

Illustration. Examine some oxide of barium, BaO, before the Bp. on Ch.

i. Formation of a metallic bead—color and malleability.

Illustration. Examine some silver oxide, AgO, before the Bp. on Ch.

Examination on Charcoal with Na₂CO₃.—Metallic compounds are often difficult to reduce with the blowpipe flame alone, and hence no bead is obtained. In order to facilitate reduction and the obtaining of a metallic bead, the substance in a finely powdered condition is mixed with four parts of sodium carbonate, Na₂CO₃, and ignited before the Bp. on Ch. The metallic compound is decomposed, the metal being transformed into the carbonate, which in turn, through the agency of the Ch. and the heat of the flame, is reduced to the free metal. Sometimes the reduction is made easier by adding to the substance about its own bulk of potassium cyanide, KCN, which takes up oxygen from the compound and is converted into potassium cyanate, KCNO.