Elements of chemistry, in two volumes / by John Murray.

  • Murray, John
Date:
1828
Catalogue details

Licence: Public Domain Mark

Credit: Elements of chemistry, in two volumes / by John Murray. Source: Wellcome Collection.

    25/768 page 13
    Gaseous ammonia extinguishes combustion ; it is in- flammable when previously mingled with atmospheric air, burning with a slight lambent flame; when kindled in mixture with oxygen gas it burns more strongly. Ammoniacal gas is largely and rapidly absorbed by wa- ter ; the water, under a mean atmospheric pressure and temperature, taking up, according to Sir H. Davy, 670 times its bulk of the gas, and acquiring a specific gravity of .875 : according to Dr Thomson, water takes up even 780 times its bulk of ammoniacal gas. Ice immediately liquefies in the gas, at the same time condenses it, and this is accompanied by the production of cold. Its solution in water is of inferior specific gravity to pure water, being usually from .900 to .936. The gas is expelled from it by an elevation of temperature of 130°; by intense cold the solution is congealed without the ammonia being sepa- rated: the congelation takes place at —40° ; and at —50° it loses all smell. It is under the form of the watery solution that ammo- nia is usually employed as a chemical agent. The solu- tion is prepared, according to the directions of the Edin- burgh Pharmacopoeia, by mixing 3 parts of newly slaked lime with 2 of muriate of ammonia reduced to powder, heating the mixture in a retort placed in a sand-bath, and connected with a receiver, in which a quantity of dis- tilled water is placed, equal in weight to the salt employ- ed. The ammoniacal gas which is generated passes over to the receiver, and is condensed by the water there. This process is intended to yield a very strong solution, but it will be found advantageous to place likewise in the retort a quantity of water equal to the weight of the salt. Mr Phillips has objected to this process, that the quanti- ty of lime is unnecessarily large, whence large vessels are required; but Dr Hope considers this excess to be use-
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