Iron enters the circulation along the whole length of the alimentary canal as the chloride and alkaline albuminate, and quickly unites with the corpuscles, as it cannot be found in the plasma. It combines with the haemoglobin, and as such alone exists in the blood. In normal blood a "course" of iron increases the richness of the blood; whilst in anaemia the rapidity of the growth of corpuscles and of the rise in value of the haemoglobin, as estimated day by day with the haemoglobin-ometer and haemacytometer, is remarkable. Iron is accordingly used as a haematinic in an endless variety of conditions in which haemoglobin is deficient, such as simple anaemia, scrofula, amenorrhoea, cardiac disease, syphilis, malarial cachexia, and convalescence from acute disease. The cautions already given respecting digestion must be faithfully respected, to secure its haematinic action over a length of time. Iron is an important constituent of many well-known mineral waters, the most important being those of Spa, Tarasp, Kissingen, Kreut-znach, Pyrmont, and St. Moritz on the Continent; Harrogate, Moffat, and Strathpeffer in this country; and the Rawley Springs, Sweet Chalybeate, and Bedford, in the United States.

3. Specific Action And Uses

Iron has no specific action on the organs apart from the blood; and the tonic effect which it produces so satisfactorily, appears to be entirely referable to its action on the blood. Abundance of oxygen is essential for every bodily and mental function; and the feeling of "tone," vigour, and mental fitness varies with the degree of oxygenation of the blood, i.e. with the quality of the blood as regards haemoglobin. Nervous, muscular, and cardiac debility are thus removed by iron, and even digestion is restored by this gastric irritant, if it can be success-fully introduced into the blood. The temperature is said to be slightly raised by iron, showing increased oxydation. Iron has also a specific effect in erysipelas, diphtheria, and other adynamic diseases, which cannot be perfectly explained. Fever is generally held to contraindieate the use of iron; and the same may be said of phthisis, except as mild forms in chronic cases.

4. Remote Local Action And Uses

Iron is excreted by almost every possible channel. As it is absorbed, so a portion of it is excreted, along the whole length of the intestine, and colours the faeces black (sulphide). Only a small amount escapes in the urine, saliva, sweat, the milk in women, the pancreatic juice, and by the various mucous surfaces. Whilst passing out of the system, iron produces a second or remote effect of an astringent kind. As regards the bowels, the clinical applications of this action are most im tant. Thus most of the salts of iron cause constipation unless combined with a purgative, such as the sulphates of magnesia and soda, or aloes; no good can be derived from iron until the bowels have been thoroughly relieved, and are acting regularly; and certain salts, such as the perchloride and pernitrate, which are more astringent to the intestines than others, may sometimes be employed to check chronic diarrhoea and dysentery, and to arrest haemorrhage from the bowel in typhoid fever. The remote astringent action of iron is increased from the fact that it is also excreted by the liver, and passes down with the bile. The urine falls somewhat in volume, but the urea and other solids, as well as the acidity, are increased. Haemorrhage from the kidney or bladder is arrested by iron, which is also beneficial in some cases of Bright's disease.

Iron similarly reduces the secretion of milk in nursing women. The remote effect of iron on the mucous surfaces renders it a valuable haemostatic in recurrent passive bleedings from the nose, uterus, and respiratory passages. As a remote astringent, it is invaluable in chronic discharges from the same and allied parts, especially in leucorrhcea.

5. Actions And Uses Of The Different Preparations Of Iron

Large as is the number of the preparations of iron, they and their special actions may be easily remembered if classified as follows:

1. Iron, Its Oxides And Carbonates

Iron, Its Oxides And Carbonates. This group comprises Ferrum Redactum, MisturaFerri Aromatica, Vinum Ferri, Ferri Carbonas Saccharata, Mistura Ferri Composita, Ferri Per-oxidum Hydratum, and Ferri Peroxidum Magneticum. These preparations possess the haematinic action of iron with but little astringency, and are accordingly selected to restore the blood, when the patient has a tendency to dyspepsia and constipation. They are the principal forms of iron used in the routine treatment of anaemia, amenorrhcea, and chlorosis in young women. Let it be observed that these solid preparations form the soluble compounds in the stomach, for absorption into the blood, as readily as do the fluid preparations belonging to the second class. The Mistura Ferri Composita, although a preparation of the protosulphate, contains the carbonate and peroxide, and is a favourite and valuable preparation for anaemia with amenorrhoea; the iron acting as a haematinic, the potash also building up the red corpuscle (the salts of which are almost entirely potassium compounds), and the myrrh possibly increasing the production of leucocytes for conversion into the red, as well as stimulating the uterus. Ferrum Redactum, the Saccharated Carbonate and the Hydrated and Magnetic Oxides, although bulky powders, are easily taken. Vinum Ferri is an agreeable preparation largely prescribed for children. The Aromatic Mixture, containing cinchona and aromatic bitters, is a valuable stomachic tonic and haematinic.

2. Compounds Of Iron With The Mineral Acids

Compounds Of Iron With The Mineral Acids. Ferri Sulphas in its various forms, Liquor Ferri Perchloridi and its preparations, and Liquor Ferri Pernitratis, are comprised in this group, which are characterised by their corrugating and astringent action. They are, therefore, chosen in all the external and internal applications of iron for local purposes, especially as haemostatics. The strong solution of the perchloride is injected into the uterus in post partum haemorrhage in the form of a watery solution (1 part to 3) with the best results. Cotton wool or lint soaked in the same solution is used for plugging deep wounds, the cavities of the nose, mouth, etc., in haemorrhage; but the action of the iron on the surfaces of wounds, and the extensive coagulation which it sets up in the veins, are both objections to its employment, unless the bleeding cannot otherwise be arrested. Internally these astringent preparations may be given in haemorrhage from the stomach or bowels, kidneys or bladder; but not, as a rule, in haemoptysis. As haematinics, the tincture or liquor of the perchloride and the pernitrate, well diluted, are much given to convalescents after the appetite has been restored, and to persons who require a tonic, as well as in passive haemorrhages and chronic inflammatory discharges, such as leucorrhoea. In ordering this class of iron salts, we must carefully observe the various precautions already mentioned in connection with digestion. Protosulphate is well borne in the form of pill (Blaud).

3. Compounds Of Iron With Vegetable Acids

Compounds Of Iron With Vegetable Acids. These are the Ferri et Ammoniae Citras, Ferrum Tartaratum, and Tinctura Ferri Acetatis. They are at once the weakest, the blandest, and the least constipating preparations of iron, and are therefore employed when only small quantities of the metal have to be given over a length of time as a tonic, or to commence a course of haematinics when the alimentary canal cannot tolerate the stronger preparations. They make but little impression upon the more severe forms of anaemia. They can be given with alkalies.

4. Compounds Of Iron With Other Active Bodies

Compounds Of Iron With Other Active Bodies. Iron is combined in the Pharmacopoeia with iodine - Ferri Iodidum; with arsenic acid - Ferri Arsenias; with phosphoric acid - Ferri Phosphas; and with quinine - Ferri et Quiniae Citras. Speaking generally, it may be said that in these preparations the iron is intended to relieve anaemia, or to act as a tonic in the sense we have described, whilst the other constituent is specifically influencing the diseased condition on which the anaemia or debility depends. Thus the iodide of iron is employed in syphilis and scrofula; the arseniate in chronic diseases of the skin, liver, etc., with a gouty, rheumatic, or malarial taint; the phosphate in diseases of the bones, such as rickets; and the compound with quinine in malarial cachexia, where it may rapidly restore the blood corpuscles. But all the preparations of this group, and especially the last, are also used as ordinary tonics, according to circumstances.

The Solution of the Persulphate of Iron is introduced solely as a source of several other preparations. Ferri Peroxidum Humidum is the best form as an antidote to arsenic, the rationale of which has been already explained.