Cupric ferrous sulphate

Cuprous thiocyanate, CuCNS.—The thiocyanate is produced by dissolving cuprous oxide or carbonate in thiocyanic acid, and by the interaction of solutions of potassium thiocyanate and a cupric salt in presence of a reducer, such as ferrous sulphate or sulphurous acid.2 It is a white substance, its solubility at 18° C. being 0 23 mg. in 1 litre of water.3 It dissolves in ammonium hydroxide and concentrated hydrochloric acid, and also in concentrated nitric acid with formation of cupric sulphate. It is employed in the preparation of aromatic thiocyanates.4... 

When the ores contain iron, it is impossible to separate the ferrous sulphate and cupric sulphate by crystallization. If the mixed sulphides are roasted at a suitable temperature, the ferrous sulphate formed is converted into oxide. Another method of separation depends on heating a solution of the two sulphates under pressure at 180° C., the ferrous salt crystallizing out.7 For agricultural purposes the removal of the iron is unnecessary. 

In alkaline solution oxidation of ferrous iron is fairly rapid,8 but certain acids retard the reaction. Ferrous sulphate, for example, in the presence of free sulphuric acid, is very stable in air. Concentrated hydrochloric acid assists the oxidation, as also do traces of certain substances, such as platinic and cupric chlorides, palladium nitrate, etc.9... 

Ammonium sulphamate (AMS) Ammonium sulphate Ammonium thiocyanate Calcium cyanamide Cupric sulphate Cupric nitrate Ferrous sulphate... 

Manganous Sulphate—Mangani anlpiui (f. ST.)—MnSO -f Aq—150 4-nl8—is forineil by the action of H.BO on MnO. Below 6 (42 .8 F.) it crvstallizes with 7 Aq, and is isomorphous with ferrous sulphate j between 7 -20 (44 .6-68 F.) it forms cryTitiUs with 5 Aq, and is isomorphous with cupric sulphate between 20 -30 f68 = -66 = F.) it cnstallizes with 4 A. It is Tose-colored, darker as the proportion of Aq increases soluble m H.O, instduble in alcohol. With the alkaliue sulphates it forma double salts, with 6 Aq. 

Supposedly there was also a wet process involving mixing a dilute solution of cupric sulphate and ferrous sulphate, in proper proportions. .. with a quantity of ferrocyanide of potassium, not in excess (Salter, 1869), though clearly this is giving one of the copper hexacyanofenate(II) pigments copper dipotassium hexacyanoferrate(II) or dicopper hexacyanoferrate(II) hydrate. Terry (1893) also discriminates between Prussian black (calcined Prussian blue) and Prussiate black, the carbonaceous residue from making yellow prussiate of potash . 

In the modern Hunt-Douglas process the ore is leached with dilute sulphuric acid, and the copper converted into cupric chloride by addition of ferrous chloride or calcium chloride. The use of the calcium salt entails removal of the calcium sulphate by filtration. The cupric salt is precipitated as cuprous chloride by reduction with sulphur dioxide, and the precipitate is converted into metallic copper by treatment with iron, or into cuprous oxide by the action of milk of lime. In this process the amount of iron needed is proportionately small, ferric hydroxide is not precipitated, and silver is not dissolved. 

The formation of the chlorides is effected in the dry way by calcination with sodium chloride or in the wet way by interaction with ferrous chloride and hydrochloric acid or with ferric chloride. The wet way is only adopted if fuel is scarce, or the escape of noxious vapours into the atmosphere is not permissible. In the dry method the ore is oxidized by a preliminary roasting, and then chloridized by calcination with sodium chloride or Abraum salts in a furnace of the reverberatory or muffle type, the principal product being cupric chloride. The Dotsch modification of the wet process, worked at Rio Tinto, depends on the action of ferric-chloride solution on a mixture of the ore with sodium sulphate and ferric chloride. The liquid drawn off from the bottom of the heaps of ore contains cuprous chloride in solution as a complex salt. The copper is liberated by the action of iron, the ferrous chloride simultaneously formed being chlorinated in towers to ferric chloride, and the product employed for moistening the heaps of ore. 

Valency and Ions.—Copper is usually considered to exhibit univalency in the cuprous compounds and bivalency in the cupric compounds. Its univalency in the cuprous compounds accords with the position of the metal in the periodic system, and is exemplified by the resemblance of the cuprous halides to the halides of silver and univalent gold, and also by the isomorphism of cuprous sulphide and silver sulphide. The bivalency of the atom in the cupric compounds is in agreement with the properties of many of its derivatives, a typical example being the isomorphism of cupric sulphate with the sulphates of ferrous iron, zinc, magnesium, and manganese. 

Characters and Tests.—Yellow crystals derived from the octohedron, permanent in the air, soluble in water, insoluble in alcohol. The aqueous solution gives a deep blue precipitate (ferric ferrocyanide ) with a ferric salt, a precipitate which is at first wUte (poti sio-ferrous ferrocyanidef), then light blue, and finally, by exposure to the air, dark blue,J with a ferrous salt and a reddish-brown precipitate (cupric ferrocyanide) with cupric sulphate. Heated with diluted sulphuric add, hydrocyanic acid vapours are evolved. 

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