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.

    169/272 (page 151)
    insoluble sulphate of baryta, and to the filtrate add ammo- nia; if no precipitate ensue, the other acids (boracic acid excepted) in the group cannot be present. Borate of baryta is soluble in ammoniacal salts, from which solution it is not precipitated on the addition of ammonia.* Arse- niate and arsenite of baryta are likewise soluble in ammo-_ niacal salts, from which solutions ammonia fails to precipi- tate them, but their presence or absence will have been determined already. If any base is present which is pre- cipitated by ammonia, it must be removed before we can employ the alkali for pointing out whether any other acid is present but sulphuric. 366. All the baryta salts mentioned in the table are colourless, with the exception of the curomat#, which is of a pale-yellow colour. 367. The following precautions must be attended to i ex- amining for this group of acids :—The first thing which claims attention is the state of the solution, viz., whether it be acid, alkaline, or neutral. When it is acid, ammonia must be added until it is slightly alkaline ; should this cause a precipitate, filter off, and to the filtrate add chloride of barium; if no precipitate ensue on the addition of am- monia, add at once the baryta salt. Should the solution be alkaline, the alkalinity proceeding from one of the fixed alkalies, it would be better to neutralize with hydrochloric acid before adding the chloride of barium. Nitrate of baryta must be substituted for chloride of barium, and the precipitate produced be digested with nitric acid, when lead, silver, or suboxide of mercury is present. The * Oxalate of baryta and fluoride of barium are soluble in ammoniaca] salts, though in a less degree than borate of baryta, and, like this latter salt, they are not precipitated from this solution by ammonia ; oxalic acid and hydrofluoric acid, as well as boracic acid, may be pre- sent, although ammonia causes no precipitate in the filtrate.