This section is from the book "Materia Medica And Therapeutics Inorganic Substances", by Charles D. F. Phillips. Also available from Amazon: Materia medica and therapeutics.
By adding an alcoholic solution of acetate of potash to one of persulphate of iron, agitating for an hour, and filtering from the precipitate of sulphate of potash, which is insoluble in spirit.
A deep-red liquid which is apt to decompose and become muddy; its taste is not unpleasant, and its degree of astringency moderate.
By adding carbonate of ammonium to ferrous sulphate, each salt being dissolved in boiling water, so as to avoid the presence of air; the precipitate is collected, washed, and rubbed with sugar.
The precipitate is at first white, then green and finally becomes red from absorption of oxygen and formation of ferric oxide. There is no ferric carbonate, but what is often sold as carbonate is a brown ferric oxyhydrate containing only a trace of the desired salt, which is very unstable and prone to oxidation; to preserve it from this as far as possible, it is rubbed up with sugar.
By heating together iron wire with twice its weight of iodine, and eight times its weight of water, until the solution becomes colorless; it is then filtered and evaporated to solidity.
A crystalline, green substance with a tinge of brown, containing about 18 per cent. water of crystallization and a little oxide of iron, without odor, deliquescent, soluble in equal parts of water, forming a greenish solution which very readily absorbs oxygen, and changes into free iodine and ferric peroxide. It is decomposed also by heat, emitting colored vapors of iodine; the altered solution may, however, be restored by warming with more iodine and iron, and may be preserved in strength by keeping a piece of iron in it; so that as iodine is liberated, it can re-combine to iodide. Syrup will preserve to a great extent, and it is in the form of syrup that it is most frequently ordered (v. p. 179); it is incompatible with alkalies and their carbonates.
A Bromide of Iron is prepared similarly by direct combination, and is sometimes prescribed, but is not yet officinal.
From a solution of sulphate by the addition of a mixed solution of arseniate, and of acetate of soda: the precipitate is filtered and dried at a low temperature to avoid oxidation. In this process, arseniate of iron, sulphate of soda, and free acetic acid are formed; without the acetate of soda, free sulphuric acid would be present, and this would dissolve the iron salt: the decomposition is complex.
Arseniate of iron is an amorphous powder, white when first formed, but becoming gray or greenish-blue from absorption of oxygen: insoluble in water; soluble in hydrochloric acid. Thrown on live coals it evolves the garlic odor of arsenic, and is essentially an arsenical remedy, for the quantity of iron in any admissible dose is insignificant.
By a process analogous to that for the arseniate; sulphate of iron is precipitated by phosphate of soda, some acetate of soda being also added to neutralize any free sulphuric acid that would be liberated from the iron salt. The precipitate is dried at low temperature to prevent oxidation.
A slate-blue amorphous powder, almost tasteless, insoluble in water, soluble in acids.
Syrupus Ferri Phosphatis (v. p. 180 ).
Another group of iron compounds may be made of the scaly preparations, which are compounds of the metal and often of some other drug in addition, with a vegetable acid, such as tartaric or citric acid.
Freshly precipitated peroxide of iron is dissolved in solution of acid tartarate of potash and allowed to stand for twenty-four hours, concentrated at a moderate temperature, and poured, when of syrupy consistence, on flat plates to solidify.
Occurs in dark garnet-colored scales; soluble in water, sparingly so in spirit. If boiled with potash or soda it deposits peroxide of iron, but is distinguished from the ammonio-citrate by not evolving ammonia under the same conditions, and also by leaving an alkaline ash.
By dissolving freshly precipitated peroxide of iron in citric acid with heat, adding ammonia to neutralization, evaporating to consistence of syrup, and then drying in thin layers on plates.
Occurs in transparent ruby-red scales, of sweet astringent taste and slightly acid reaction, soluble in water, almost insoluble in spirit. If boiled with soda or potash, it evolves ammonia, but alkaline carbonates do not readily decompose it, and it may, therefore, be given with them in effervescence with citric acid: the iron salt should be put into the acid solution.