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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    not project over the edge of the funnel, especially if the substance in the filter requires to be washed. Should the first portions of the liquid which pass through the filter not be perfectly bright, which is frequently the case, they must be returned to the filter, and this must be repeated until it is perfectly bright. The liquid which passes through the filter is called the jiltrate. DECANTATION. 41. When the solid particles are very heavy, the’ super- natant liquid can be perfectly separated, without passing it through a filter, by simply inclining the vessel, so as to allow the fluid to pass away unattended by the precipitate, or by removing the fluid by a syphon. 42. The separation in this way of a solid from a fluid is called decantation. 43. Too great attention cannot be paid to the washing of precipitates when they are required for further examination. After the precipitate has been thrown upon the filter, a stream of water must be projected from the wash-botile upon it, from time to time, until it is perfectly freed from soluble matter ; this is sooner accomplished if hot water be employed. Hot water may therefore be used in all cases unless the contrary be expressly stated. EVAPORATION. 44. This process is used for the purpose of obtaining matter in a solid state from solutions. By the aid of heat, the volatile fluid passes off in the gaseous form, whilst the non-volatile matter remains behind. 45. If the evaporation be conducted slowly, the solid matter will frequently, on being deposited, assume a crys-