Ferrous copper sulphate

Ferrous copper sulphate, (Fe, Cu)S04.H20, or CuS04.2FeS04.3Ha0, occurs in yellowish brown crystals which are not hygroscopic in ordinary air, but take up water in a warm atmosphere saturated with moisture.6... 

For some non-ferrous metals (copper, lead, nickel) the attack by sulphuric acid is probably direct with the formation of sulphates. Lead sulphate is barely soluble and gives good protection. Nickel and copper sulphates are deliquescent but are gradually converted (if not leached away) into insoluble basic sulphates, e.g. Cu Cu(OH)2)3SO4, and the metals are thus protected after a period of active corrosion. For zinc and cadmium the sulphur acids probably act by dissolution of the protective basic carbonate film. This reforms, consuming metal in the process, redissolves, and so on. Zinc and cadmium sulphates are formed in polluted winter conditions whereas in the purer atmospheres of the summer the corrosion products include considerable amounts of oxide and basic carbonate. ... 

On ferrous metals immersion deposition in the copper sulphate bath produces non-adherent deposits, and a cyanide copper undercoat is therefore normally used. Where the use of a cyanide strike cannot be tolerated, an electroplated or immersion nickel deposit has been used . Additions of surface-active agents, often preceded by a sulphuric acid pickle containing the same compound, form the basis of recent methods for plating from a copper sulphate bath directly on to steel ". 

Ink (melanos) was made from lampblack or soot from burning resins, mixed with gum or glue. Dioscorides mentions that chalcanthum is added. This addition is difficult to understand. Chalcanthum as we have seen was a term including copper sulphate, ferrous sulphate and mixtures of the two. If a solution of nutgalls or other solution of tannin were used, the addition would be comprehensible... 

Similarly, when sulphur is heated with 2 to 3 times its weight of dehydrated ferrous sulphate or copper sulphate, sulphur dioxide is produced together with the sulphide of the metal 5... 

Copper, Zinc, and Alkali Salts. — Dissolve 5 gm. of ferrous ammonium sulphate in 50 cc. of water, add 5 cc. of nitric acid (sp. gr. 1.3), and boil the solution for a few minutes then add to the liquid 15 cc. of ammonia water, let stand for about one hour, and filter. The filtrate must be colorless (copper). 

Many alloys and compounds have an equal claim to be considered in two or more volumes of this series, but this would entail unnecessary duplication. For example, alloys of copper and tin might be dealt with in Volumes II. and V. respectively. Similarly, certain double salts—such, for example, as ferrous ammonium sulphate—might very logically be included in Volume II. under ammonium, and in Volume IX. 

E. P. Alvarez 2 found that the pemitrates react with soln. of lead acetate (white precipitate), silver nitrate (white precipitate), mercurous nitrate (white precipitate with rapid decomposition), mercuric chloride (red precipitate), copper sulphate (blue precipitate), zinc and cadmium sulphates (white precipitate), bismuth nitrate (white precipitate), gold chloride (slight effervescence and escape of oxygen), manganous chloride (pink precipitate), nickelous chloride or sulphate (greenish-white precipitate), cobaltous nitrate and chloride (pink precipitate), ferrous sulphate (green or bluish-green precipitate), ferric chloride (red ferric hydroxide), and alkaline earth chlorides (white precipitates). The precipitates are all per-salts of the bases in question. 

An acid of sp. gr. 1-517 at 15°/4° absorbs 0-88 per cent, of nitric oxide so that the coefi. of absorption is 12-5. The speed of absorption varies with the cone, of the acid. C. A. Winkler obtained no absorption of nitric oxide by the hydrate of sulphuric acid and M. Berthelot said that nitric oxide is very slightly soluble in cone, sulphuric acid. O. Lubarsch made some observations on this subject. E. Desbassayns de Richemont said that if the sulphuric acid contains a little ferrous sulphate, nitric oxide imparts to it a red colour and if copper sulphate, a violet colour. In the latter case, W. Manchot found that the coloration is due to the formation of an easily dissociated copper nitrosylsulphate, CuSO4.NO— vide infra. For the corresponding compound with ferrous sulphate, vide infra. G. Lunge found that 1 c.c. of sulphuric acid of sp. gr. 1-84 absorbs 0-035 c.c. of nitric oxide, and an acid of sp. gr. 1-50, 0-017 c.c. and O. F. Tower, v vol. of nitric oxide at 760 mm. absorbed by one vol. of acid 18° and H2S04 per cent. 

Sometimes the ore must be pretreated before it will adsorb the additive satisfactorily for example, zinc sulphide must be pretreated with dilute copper sulphate solution, which deposits copper on the ore surface by electrochemical action. Specificity of flotation may also be achieved by the addition of depressants for example, cyanide ions prevent ferrous sulphide and zinc sulphide from floating but allow... 

Oxygen is readily evolved at the ordinary temperature on adding water to a mixture of bleaching powder and an alkali or alkaline earth peroxide in the presence of a catalyst such ns ferrous or copper sulphate. If the solid mixture is pressed into small lumps or cubes, it may be used in a Kipp s apparatus and thus afford a convenient method of preparing the gas for lecture or laboratory purposes.4... 

Constitution of Pyrites and Marcasite.—When marcasite is heated to 200° C. in sealed tubes with copper sulphate solution, the product contains iron m the ferrous state only. Pyrites, under similar treatment, yields about 20 per cent, of its iron in the ferrous form, the remainder being ferric. It has therefore been suggested2 that marcasite is represented by the formula 3... 

When a crystal of copper sulphate, CuS04.5H20, is introduced into a supersaturated solution of ferrous sulphate, triclinic crystals of the pentahydrate,3 FeS04.5H20, separate out, isomorphous with the copper salt, and of density 1 89. 

The origin of the brown colour has been a matter of discussion. The monohydrates of ferrous sulphate and copper sulphate are white and pale blue respectively, so cannot be the direct cause of the colour. Neither is the brown due to ferric salts or to cuprous oxide. The suggestion has been made 7 that it is the result of an oscillation of electrons due to the presence of metals in different stages of oxidation, the copper being saturated whilst the iron is not,... 

Stortenbeker bas also studied the mixed crystals formed by cadmium sulphate and ferrous sulphate by zinc sulphate and magnesium sulphate by magnesium sulphate and ferroiis sulphate by copper sulphate and manganese sulphate by cobalt chloride and manganese chloride. We shall limit ourselves to referring the reader to these valuable memoirs. 

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