Potassium ferrous oxalate

Certain iron compounds have been used for reduction. Ferrous sulphate in aqueous solution, with ammonia, baryta, or sodium hydroxide, may be used for reducing, as also may ferrous potassium oxalate in neutral, alkaline, or weakly acid solution. 

Ferrous potassium oxalate can be utilised in these cases with good results."1... 

Gold is estimated quantitatively by methods similar to those employed in its qualitative detection. It can be precipitated with a standard solution of ferrous sulphate or potassium oxalate,10 and the excess estimated by titration with permanganate or precipitated with stannous chloride in alkaline solution, the excess of tin being ascertained by titration with iodine.11 Other methods are direct titration with stannous... 

In this connection it must be pointed out that standard samples which have been analysed by a number of skilled analysts are commercially available. These include certain primary standards (sodium oxalate, potassium hydrogenphthalate, arsenic(III) oxide, and benzoic acid) and ores, ceramic materials, irons, steels, steel-making alloys, and non-ferrous alloys. 

Oxalate is found to be a frequent impurity in pharmaceutical substances belonging to the category of either organic acids e.g.. anhydrous citric acid, tartaric acid or salts of organic acids e.g., ferrous gluconate, sodium citrate, potassium citrate and sodium cromoglycate. The presence of this impurity is due to the following two prime factors, namely ... 

Oxidation processes involving the subsequent titration of an excess of ferrous sulphate,2 oxalic acid (in the presence of silver sulphate as catalyst), titanous chloride,4 or of the quantity of iodine liberated from potassium iodide,5 are also available but are less satisfactory. In the last-named method a large excess of potassium iodide is necessary to obtain complete reaction in a short time. The reaction may be accelerated by the addition of potassium chloride6 or ammonium chloride with 20 per cent, by weight of the latter salt present a large excess of the iodide is not necessary and the liberated iodine may be titrated after fifteen minutes.7... 

Selenious acid readily decomposes potassium permanganate, but analytical results are untrustworthy in the presence of more than a limited quantity of sulphuric acid.1 The oxidation should be carried out at 50° C., a known quantity of 0-lN potassium permanganate being used and the excess determined either by means of standard oxalic acid solution or by electrometric titration with ferrous sulphate. In the presence of tellurium, the latter is also oxidised and should be determined in a separate sample by oxidation with potassium di-chromate, which does not oxidise the selenium, and the necessary deduction can then be made.2... 

Nitrates. — Add gradually 1 gm. of crystallized oxalic acid to a solution of 0.5 gm. of potassium permanganate in 5 cc. of water, heat to 50 to 60° C., and filter. On overlaying 1 cc. of ferrous sulphate solution on a mixture of 2 cc. of the clear colorless filtrate and 2 cc. of concentrated sulphuric acid, no dark-colored zone should format the contact-surfaces of the two liquids. 

When you put the exposed blueprint papers into the developing solution, there was a reaction between the ferrous oxalate and the potassium ferricyanide. This reaction caused the blue color to appear. 

The presence of gold in any of the precipitates described can be detected by solution in aqua regia, and reduction to metallic gold by various reagents, including ferrous chloride, ferrous sulphate, mercurous nitrate, stannous chloride, hypophosphorous acid, oxalic add,3 sulphurous acid, hydrogen peroxide and potassium hydroxide, formaldehyde, and hydroxylamine hydrochloride.4... 

Mordant 1/2-in. strips of test cloth in the following mordants, which are 0.1 M solutions of the indicated salts. Immerse pieces of cloth in the solutions, which are kept near the boiling point, for about 15 to 20 min or longer. The mordants are ferrous sulfate, stannous chloride, potassium dichromate, copper sulfate, and potassium aluminum sulfate (alum). The alum and dichromate solutions should also contain 0.05 M oxalic acid. These mordanted pieces of cloth can then be dyed with alizarin (1,2-dihy-droxyanthraquinone) and either Methyl Orange or Orange II in the usual way. 

Salts Compounds formed by the union of acids and bases, by the action of alkalies upon metals, or by the direct union of elements. The term is often incorporated in the common name of salts used as pharmaceuticals bitter salts, epsom salt, or Seidlitz salt (magnesium sulfate), preparing salt (sodium stannate), Preston s salts (ammonium chloride), Rochelle salt or Seignette s salt (potassium and ammonium tartrate), salt of Mars (ferrous sulfate), salt of Saturn (lead acetate), salt of tartar (potassium carbonate), salt of tin (stannous chloride), salt of wisdom (mercury bichloride and ammonium chloride), sore-throat salt (fused potassium nitrate), vinegar salts (calcium acetate), and vomiting salt (zinc sulfate). The term is also applied to some acids, such as salt of lemon or sour salt (citric acid), salt of sorrel (oxalic acid), and spirit of salt (muriatic acid). ... 

Materials Solutions of ferrous ammonium sulphate, of potassium dichromate, of potassium ferrocyanide, of potassium ferricyanide potassium dichromate, oxalic acid. 

A number of double oxalates are known. Potassium ferrous oxalate, K2Fe (0204)2, is an active reducing agent, which is used as a developer for photographic plates. Potassium ferric oxalate, K3Fe(C204)3, is rapidly reduced by sunlight to the ferrous salt —... 

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