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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    talline form. The operation, is then termed crystalliza- tion. 46, This operation is frequently conducted for the pur- pose of obtaining a liquid in a more concentrated form, by volatilizing a portion only.of the fluid. Vessels are con- structed expressly for the purpose, called evaporating dishes. DISTILLATION. 47, This operation, like the former one, consists in the separation of a volatile from a less volatile fluid, or in, the separation of a liguid from a solid. But in evaporation no attention is paid to the volatilized fluid, whilst in distillation it is frequently the only substance required. A distilling apparatus is therefore so constructed as to allow the evapo- rated fluid to be collected, which is called the distillate. It consists of three parts :—1. A vessel in which the liquid to be distilled is heated. 2; An apparatus in which the vapour is cooled and condensed. 3: A vessel for receiving the dis- tillate. 48. On a small scale, glass retorts are employed; but in the distillation of large quantities, copper stills are usually substituted for them. IGNITION. 49. By this operation volatile is separated from non- volatile solid matter; it requires the application of a high temperature, and must be conducted in crucibles. This process 18 therefore an evaporation of solid bodies. SUBLIMATION. 50. By sublimation we effect not only the separation of volatile from less volatile solid matter, but by cooling we