Manual of qualitative analysis / by Robert Galloway.

  • Galloway, Robert.
Date:
1861
Catalogue details

Licence: Public Domain Mark

Credit: Manual of qualitative analysis / by Robert Galloway. Source: Wellcome Collection.

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    with noise. It also includes the oxidation of a substance by a reagent, in the dry way, on account of the slight explo- sions which frequently attend this kind of oxidation. THE BLOWPIPE. 55. The mouth blowpipe is a small instrument which is employed for directing a fine and continuous stream of air into the flame of a wax candle or oillamp. By the flame thus produced two reverse chemical operations may be per- formed, viz., oxidation and reduction. 'The flame is there- fore distinguished by these properties into the outer or oxidizing flame and the inner or reducing flame. 56. In the oxidizing flame, the inflammable vapour is in a state of complete combustion, being supplied and mixed with an excess of atmospheric air. From the high tempe- rature resulting from the perfect combustion of the inflam- mable vapour, and likewise from the excess of oxygen, all the requisite conditions are present for causing substances with an affinity for that element to enter into union with it. 57. In the reducing or deoxidizing flame the inflammable vapour is in an incomplete state of combustion, due to a deficiency of atmospheric air; hence any metallic oxide placed in this portion of the flame is robbed of its oxygen by the inflammable vapour, which requires that element for its combustion. 58. A reducing flame is obtained by keeping the nozzle of the blowpipe in an inclined direction, parallel to the surface of the wick, and just touching the exterior surface of the flame. An oxidizing flame is obtained by keeping the nozzle of the blowpipe at the same inclination as in the former case, and introducing it into the flame to about one third the breadth of the wick, at such a distance only from the