Licence: Public Domain Mark
Credit: Qualitative chemical analysis / by C. Remigius Fresenius. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![PEOTOXIDE OF MANGANESE. [§ 107. oxygen from the air. Ammonia precipitates half only of the manganese as hydrate (comp. § 98, 4, p. 99). Ammonia and carbonate ot ammonia do not redissolve this precipitate; but the presence of cmonde ot ammonium prevents the precipitation by ammonia alto- gether and that by potassa partly; solution of chloride of ammonium redissolves only those portions of already formed precipitates which have not yet undergone peroxidation. The dissolution of the hydrate in chloride of ammonium is owing to the disposition of the salts of protoxide of manganese to form double salts with salts of ammonia. Ihe ammoniacal solutions of these double salts turn brown on exposure to aii-, and deposit dark-brown hydrate of protosesquioxide ot manganese. i 1 7. If potassa or soda or acetate of soda is added to a solution of a manganese salt and then chloride of soda or a solution of toromme, and the mixture heated, the whole of the manganese separates as the brownish-black hydrated peroxide. P Non-volatile organic acids impede or prevent the precipitation ot the hydrates of manganous and manganic oxides. Sugar impedes the precipitation of manganous oxide but not of the peroxide. 8. Carbonate of ammonia throws down white carbonate of protoxide of manganese, MnO,CO.,-t-HO [MnC03,H.,0]. The precipitation is complete after some time, even in presence of chloride of ammonium. Carbonates of the fixed alkaUes give a white precipitate which is either hydrated carbonate of manganese, hydrated protoxide of manganese, or a mixture of these, accord- ing to circumstances. When freshly precipitated, it dissolves in chloride of ammonium solution, but it is insoluble in excess of the precipitant. N.B. Non-volatile acids interfere with or prevent the precipitation by fixed alkaline carbonates, whilst the precipitation with carbonate of ammonia is retarded, but not prevented. 9. Perrocyanide of potassium throws down ferrocyanide of manganese, Mn.Cfy [Mn,Fe(CN),], as a reddish-white precipitate, soluble in hydrochloric acid. 10. Ferricyanide of potassium precipitates brown ferricyanide of manganese, Mn,Cfdy [Mn3Fe,(CN),2], insoluble in hydrochloric acid or ammonia. 11. If a few drops of a solution containing protoxide of manganese, .and free from chlorine, are sprinkled on binoxide of lead, nitric acid free from chlorine added, and the mixture boiled and allowed to settle, the solution acquires a red colour, from the formation of per- manganic acid (Hoppe-Seyler). 12. Carbonate of baryta does not precipitate protoxide of man- ganese from aqueous solutions of its salts by digestion in the cold, except in the case of sulphate of protoxide of manganese. 13. If any compound of manganese, in a state of minute division, is fused with 2 to 3 parts of carbonate of soda on a platinum wire, or on a small stiip of platinum foil (heated by dii^ecting the flame on to the lower surface), in the outer flame of the Bunsen or blowpipe, man- ganate of soda, ]SraO,Mn03 [Na,MnO,], is formed, which makes the melt appear green while hot, and of a bluish-green tint after cool- ing, the bead at the same time losing its transparency. This reaction enables us to detect the smallest traces of manganese.](https://iiif.wellcomecollection.org/image/b21966953_0146.jp2/full/800%2C/0/default.jpg)
