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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    ances, into erystalline, pulverulent, flocculent, curdy, and gelatinous. The terms turbid and turbidity are applied when the precipitate is so small that it cannot be distin- guished, except by impairing the transparency of the fluid. 37. The separation of precipitates from liquids is, with some few exceptional cases, much assisted by the applica- tion of heat and agitation. The operation, when performed as an analytical operation, is conducted in test-tubes, which, from their transparency, admit of an inspection of the process. FILTRATION AND DECANTATION. 38. These terms are applied to a modification of the same operation—viz., the mechanical separation of fluids from solid matter mixed with them. FILTRATION. 39. In filtration, the separation of the fluid from the solid matter is accomplished by passing it through filtering paper of a proper size and shape, supported in a funnel. The pores of the paper permit the fluid to pass through; whilst the solid matter, being prevented, remains behind. 40. To prepare a filter, take a small piece of filtering paper (the best white blotting paper), and fold it twice, from side to side; then round off with scissors the project- ing corners, so that the paper may fall wholly within the funnel; moisten the paper when placed within the funnel, and then carefully pour the liquid to be filtered upon it. The funnel, when large quantities have to be filtered, is supported in one of the rings of the retort stand; but in the ordinary filtrations required in qualitative analysis, it may rest on the mouth of a test-tube. The filter should