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.

    189/272 (page 171)
    line precipitate of phosphate of magnesia and ammonia con- firms the presence of phosphoric acid.” (Hresenius.) Oxatic Acrp (HO, C,0,, or HO, 0). 430. Oxalic acid crytallizes from its aqueous solutions in four-sided prisms. These crystals contain three atoms of water, of which one is essential (HO, C,0, + 2aq.). When warmed, the 2 atoms of non-essential water (water of crys- tallization) are given off, and the hydrate of oxalic acid re- mains as a white powder, which melts at 350°, and, when further heated, sublimes—a portion, however, being decom- posed. It is very soluble in water, and highly poisonous. It is usual to place it in the list of organic acids ; but since its salts upon ignition leave no carbonaceous residue, it has been included in the list of inorganic acids. 431. All the oxalates are decomposed at a red heat, the oxalic acid being resolved into carbonic acid and carbonic oxide. If the base with which the acid is combined be an alkali or an alkaline earth, it is left as a carbonate; the other bases are left either in an oxidized or metallic state, according to their greater or less affinity for oxygen. 432. Lime-water and all the soluble salts of lime produce in solutions of oxalic acid and the oxalates, even if highly diluted, a white precipitate of OXALATE OF LIME, which is insoluble in acetic acid. 433. When concentrated sulphurie acid is added to dry oxalic acid or an oxalate, it withdraws the constitutional water in the one case and the base in the other from the anhydrous acid (C,03), which, being incapable of existing alone, splits up into CARBONIC ACID and CARBONIC OXIDE. The two gases escape with effervescence ; and if a light be applied as they issue from the mouth of the tube, the car- bonic oxide will burn with a blue flame.