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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    bring the volatile matter back: to the solid state, and in this state it is called the sublimate. 51. This process is: therefore a distillation of solid bodies. FUSION. 52. This term is applied to the liquefaction of a solid, by the mere application of heat. It is also used for the decom- position of solids in the “ dry way.” 53. By this operation we are able to resolve insoluble substances into forms, which admit of solution. This is accomplished by causing their proximate elements to unite with bodies the compounds of which will be capable of solu- tion. Thus sulphate of baryta, which, from its insolubility both in water and acids, resists the action of reagents in the fluid state, is decomposed in this way. It is mixed with three or four times its own weight of dry carbonate of soda, and the mixed mass exposed in a crucible for some time to a high temperature. The two salts mutually suffer decom- position when placed in these conditions, the sulphuric acid passing over to the soda whilst the carbonic acid unites with the baryta. If the fused mass be treated with water, the sulphate of soda dissolves in that liquid, whilst the carbonate of baryta, being insoluble, remains behind. This substance, after being well washed, may be dissolved in hydrochloric or nitric acid. The decomposition of substances in the dry way requires, in most cases, a higher temperature than that which:a small spirit lamp affords. When a limited amount of heat can only be obtained, it is better to employ a mixture of equal parts of carbonate of soda and carbonate of potash, instead of the former salt alone. DEFLAGRATION. 54. This term is applied to all decompositions attended