(a) Ferrum tartaratum, dark red scales, soluble in water.
(b) Ferri et quininae citratis, greenish yellow scales soluble in water.
(c) Ferri et ammonii citratis, red scales soluble in water, from which is prepared Vinum ferri citratis (ferri et ammonii citratis 1 gr., orange wine 1 fl. dr.).
Substances containing tannic or gallic acid turn black when compounded with a ferric salt, so it cannot be used in combination with vegetable astringents except with the infusion of quassia or calumba. Iron may, however, be prescribed in combination with digitalis by the addition of dilute phosphoric acid. Alkalis and their carbonates, lime water, carbonate of calcium, magnesia and its carbonate give green precipitates with ferrous and brown with ferric salts.
Unofficial preparations of iron are numberless, and some of them are very useful. Ferri hydroxidum (U.S.P.), the hydrated oxide of iron, made by precipitating ferric sulphate with ammonia, is used solely as an antidote in arsenical poisoning. The Syrupus ferri phosphatis Co. is well known as “Parrish’s” syrup or chemical food, and the Pilulae ferri phosphatis cum quinina et strychnina, known as Easton’s pills, form a solid equivalent to Easton’s syrup.
There are numerous organic preparations of iron. Ferratin is a reddish brown substance which claims to be identical with the iron substance found in pig’s liver. Carniferrin is another tasteless powder containing iron in combination with the phosphocarnic acid of muscle preparations, and contains 35% of iron. Ferratogen is prepared from ferric nuclein. Triferrin is a paranucleinate of iron, and contains 22% of iron and 212% of organically combined phosphorus, prepared from the casein of cow’s milk. Haemoglobin is extracted from the blood of an ox and may be administered in bolus form. Dieterich’s solution of peptonated iron contains about 2 gr. of iron per oz. Vachetta has used the albuminate of iron with striking success in grave cases of anaemia. Succinate of iron has been prepared by Hausmann. Haematogen, introduced by Hommel, claims to contain the albuminous constituents of the blood serum and all the blood salts as well as pure haemoglobin. Sicco, the name given to dry haematogen, is a tasteless powder. Haemalbumen, introduced by Dahmen, is soluble in warm water.
Therapeutics.
Iron is a metal which is used both as a food and as a medicine and has also a definite local action. Externally, it is not absorbed by the unbroken skin, but when applied to the broken skin, sores, ulcers and mucous surfaces, the ferric salts are powerful astringents, because they coagulate the albuminous fluids in the tissues themselves. The salts of iron quickly cause coagulation of the blood, and the clot plugs the bleeding vessels. They thus act locally as haemostatics or styptics, and will often arrest severe haemorrhage from parts which are accessible, such as the nose. They were formerly used in the treatment of post partum haemorrhage. The perchloride, sulphate and pernitrate are strongly astringent; less extensively they are used in chronic discharges from the vagina, rectum and nose, while injected into the rectum they destroy worms.
Internally, a large proportion of the various articles of ordinary diet contains iron. When given medicinally preparations of iron have an astringent taste, and the teeth and tongue are blackened owing to the formation of sulphide of iron. It is therefore advisable to take liquid iron preparations through a glass tube or a quill.
In the stomach all salts of iron, whatever their nature, are converted into ferric chloride. If iron be given in excess, or if the hydrochloric acid in the gastric juice be deficient, iron acts directly as an astringent upon the mucous membrane of the stomach wall. Iron, therefore, may disorder the digestion even in healthy subjects. Acid preparations are more likely to do this, and the acid set free after the formation of the chloride may act as an irritant. Iron, therefore, must not be given to subjects in whom the gastric functions are disturbed, and it should always be given after meals. Preparations which are not acid, or are only slightly acid, such as reduced iron, dialysed iron, the carbonate and scale preparations, do not disturb the digestion. If the sulphate is prescribed in the form of a pill, it may be so coated as only to be soluble in the intestinal digestive fluid. In the intestine the ferric chloride becomes changed into an oxide of iron; the sub-chloride is converted into a ferrous carbonate, which is soluble. Lower down in the bowel these compounds are converted into ferrous sulphide and tannate, and are eliminated with the faeces, turning them black. Iron in the intestine causes an astringent or constipating effect. The astringent salts are therefore useful occasionally to check diarrhoea and dysentery. Thus most salts of iron are distinctly constipating, and are best used in combination with a purgative. The pill of iron and aloes (B.P.) is designed for this purpose. Iron is certainly absorbed from the intestinal canal. As the iron in the food supplies all the iron in the body of a healthy person, there is no doubt that it is absorbed in the organic form. Whether inorganic salts are directly absorbed has been a matter of much discussion; it has, however, been directly proved by the experiments of Kunkel (Archiv für die gesamte Physiologie des Menschen und der Tiere, lxi.) and Gaule. The amount of iron existing in the human blood is only 38 gr.; therefore, when an excess of iron is absorbed, part is excreted immediately by the bowel and kidneys, and part is stored in the liver and spleen.
Iron being a constituent part of the blood itself, there is a direct indication for the physician to prescribe it when the amount of haemoglobin in the blood is lowered or the red corpuscles are diminished. In certain forms of anaemia the administration of iron rapidly improves the blood in both respects. The exact method in which the prescribed iron acts is still a matter of dispute. Ralph Stockman points out that there are three chief theories as to the action of iron in anaemia. The first is based on the fact that the iron in the haemoglobin of the blood must be derived from the food, therefore iron medicinally administered is absorbed. The second theory is that there is no absorption of iron given by the mouth, but it acts as a local stimulant to the mucous membrane, and so improves anaemia by increasing the digestion of the food. The third theory is that of Bunge, who says that in chlorotic conditions there is an excess of sulphuretted hydrogen in the bowel, changing the food iron into sulphide of iron, which Bunge states cannot be absorbed. He believes that inorganic iron saves the organic iron of the food by combining with the sulphur, and improves anaemia by protecting the organic food iron. Stockman’s own experiments are, however, directly opposed to Bunge’s view. Wharfinger states that in chlorosis the specific action of iron is only obtained by administering those inorganic preparations which give a reaction with the ordinary reagents; the iron ions in a state of dissociation act as a catalytic agent, destroying the hypothetical toxin which is the cause of chlorosis. Practical experience teaches every clinician that, whatever the mode of action, iron is most valuable in anaemia, though in many cases, where there is well-marked toxaemia from absorption of the intestinal products, not only laxatives in combination with iron but intestinal antiseptics are necessary. That form of neuralgia which is associated with anaemia usually yields to iron.
IRON AGE, the third of the three periods, Stone, Bronze
and Iron Ages, into which archaeologists divide prehistoric
time; the weapons, utensils and implements being as a general
rule made of iron (see Archaeology). The term has no real
chronological value, for there has been no universal synchronous
sequence of the three epochs in all quarters of the world. Some
countries, such as the islands of the South Pacific, the interior
of Africa, and parts of North and South America, have passed
direct from the Stone to the Iron Age. In Europe the Iron
Age may be said to cover the last years of the prehistoric and
the early years of the historic periods. In Egypt, Chaldaea,
Assyria, China, it reaches far back, to perhaps 4000 years before
the Christian era. In Africa, where there has been no Bronze
Age, the use of iron succeeded immediately the use of stone.
In the Black Pyramid of Abusir (VIth Dynasty), at least 3000
B.C., Gaston Maspero found some pieces of iron, and in the
funeral text of Pepi I. (about 3400 B.C.) the metal is mentioned.
The use of iron in northern Europe would seem to have been
fairly general long before the invasion of Caesar. But iron was
not in common use in Denmark until the end of the 1st century
A.D. In the north of Russia and Siberia its introduction was
even as late as A.D. 800, while Ireland enters upon her Iron Age
about the beginning of the 1st century. In Gaul, on the other
hand, the Iron Age dates back some 800 years B.C.; while in
Etruria the metal was known some six centuries earlier. Homer
represents Greece as beginning her Iron Age twelve hundred
years before our era. The knowledge of iron spread from the
south to the north of Europe. In approaching the East from
the north of Siberia or from the south of Greece and the Troad,
the history of iron in each country eastward is relatively later;
while a review of European countries from the north towards
the south shows the latter becoming acquainted with the metal
earlier than the former It is suggested that these facts support
the theory that it is from Africa that iron first came into use.
The finding of worked iron in the Great Pyramids seems to
corroborate this view. The metal, however, is singularly scarce
in collections of Egyptian antiquities. The explanation of this
would seem to lie in the fact that the relics are in most cases
the paraphernalia of tombs, the funereal vessels and vases, and
iron being considered an impure metal by the ancient Egyptians
it was never used in their manufacture of these or for any religious
purposes. This idea of impurity would seem a further proof
of the African origin of iron. It was attributed to Seth, the
spirit of evil who according to Egyptian tradition governed the
central deserts of Africa. The Iron Age in Europe is characterized
by an elaboration of designs in weapons, implements and
utensils. These are no longer cast but hammered into shape,
and decoration is elaborate curvilinear rather than simple
