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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![that the protosulphide of ii-on separates as a \MoVvveci^te. Chloride If ammoLm promotes the precipitation most mate™^^^^^^ acids su^ar, &c., clieck the precipitation by alkalies _ of f errocyanide of potassium andiron, KFe3Cfy, [K Fe3(FeO«iN y, which, on exposure to the air, absorbs oxygen and speedily acquires a blue colour. Nitric acid or chlorine converts it immediately into Prussian blue, ^^^^^^^^^ ^ ^ ^^^^ ^ j,,Cl + 2Fe,Cfy3 r3K Fe (FeC N .),+4CU = 6KCI + FeCl,+2Fe4(FeC6N5)3]. 8 PerricVanide of potassium produces a splendid blue precipitate • of ferrfcyankW i/on, Fe3Cfdy [Fe^lFe^C^.N,,)]. This precipitate does not di^er in colour from Prussian blue. It is -sd-^le in hydro • chloric acid, but is readily decomposed by potassa. ^|S^1^ ^^^^ .solutions, the reagent produces merely a deep ^l^fg^^f ,9«l°^^5^°fJ^^,,^ 9 Sikphocyanate of potassium does not alter solutions of ferrous • nxide free from ferric oxide. „ 10 Carbonate of baryta does not precipitate solutions of ferrous oxide in the cold, with the exception of the sulphate _ -^--^^ 11 Borax dissolves protoxide of iron compounds m the oxidizmg flame, giving beads varying in colour from yeUow to dark red; when cold, tlfe beads vary from colourless to dark yellow In the mner flame, the beads change to bottle-green, owing to the reduction of the newly- formed sesquioxide to protosesquioxide Microcosmic salt shows a .similar reaction ; the beads produced with this reagent lose then^ colour on cooling still more completely than those obtained with borax; the signs -of reduction in the reducing flame are also less marked 12 When redviced on the stick of charcoal (p. 24), compounds ot protoxide of iron give a dull black powder, which is attracted by a magnetised knife. The reduced metal, when dissolved m a few drops ot aqua regia, gives a yellow solution which can be further tested accordmg ito § 111. § 111. /. Ferric Oxide or Sesquioxide of Iron, Pe,03 [Fe.O,]- 1. The native crystallized ferric oxide is steel-gray; the native as ■well as the artificially prepared ferric oxide when triturated gives a ■brownish-red powder; the colour of hydrate of ferric oxide is more inclined to reddish-brown. Both ferric oxide and its hydrate dis- solve in hydrochloric, nitric, and sulphuric acids; the hydrate dis- solves readily in these acids, but the anhydrous sesquioxide dissolves with greater difficulty, and completely only after long heating with the acid. Perrosoferric oxide or protosesquioxide of iron, QUAL. ^](https://iiif.wellcomecollection.org/image/b21966953_0153.jp2/full/800%2C/0/default.jpg)
