Lessons in qualitative chemical analysis / by F. Beilstein ; translated from the fifth edition, with copious additions ... by Charles O. Curtman.

  • Beilstein, Friedrich Konrad, 1838-1906.
Date:
1883
Catalogue details

Licence: Public Domain Mark

Credit: Lessons in qualitative chemical analysis / by F. Beilstein ; translated from the fifth edition, with copious additions ... by Charles O. Curtman. Source: Wellcome Collection.

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    BLOWPIPE. t which is forced into the tube by pressure from the cheeks alone, not by HIf>wing from the longs, and is replenished from time to time without Interrupting the blowing, the respiration being carried on through the nose. A brge candle, an oil lamp with Mat wiek, or the luminous flame of the Himsen lamp (especially when produced by a special flat blowpipe burner) may be used with best advantage for the reducing operations, while, for oxidation, an alcohol flame or the non-luminous «ras flame are preferable. By the current of air from the blowpipe the flame is Mown sideways and slightly downward, and is rendered long and narrow. It is supplied with an extra supply of oxygen so as to produce a more intense combustion of its carbonaceous particles. The outer part of the flame, containing the largest supply of oxygen is used for oxidizing metals, etc., while the part nearest to the base of the flame, baring more carbonaceous matter, yet unbnrnt, serves for reduction of oxides. The operator may, at will, produce a flame in which either the oxidizing or the reducing Influence is Intensified, accompanied with a high heat. To produce a Strong reducing flame, a large flame is selected (the gas turned on more freely) and the jet of the blowpipe held just outside the flame, a little above its base, while a moderate current of air serves to lilt the flame, without depriving it of the luminous appearance, Indicating the presence of incandescent carbon, A lesser flame suits best for oxidizing. The jet of the blow- pipe is then held a little inside of the flame, and a stronger current passed so as to supply oxygen enough for complete combustion of the carbon. The flame becomes nonduminous, its point of highest heat is at the apex of the inner cone, and substances, to be oxidized, are held a little beyond this point. To support substances in the flame we generally use charcoal, made of pine or otner soft wood, for reduction experiments, and platinum wire or foil for oxidation. Many operations, for- merly effected in the blowpipe (lame, are now more conveniently performed in the flame of the Bunsen gas lamp. Exercises. Select a smooth piece of charcoal, about 70 millimetres long, 40 Mm. broad and 20 Mm. in thickness; near the corner, that will be held nearest to the flame, scoop out a small, shallow cavity. Into this place a very small crystal of potassium nitrate and direct the point of the blowpipe flame