Ferrum, the Mars of the alchemists, is one of the prominent constituents of the animal body, being present in considerable quantity in the blood. It is present in many articles of daily food, and when given in excess to men or animals its first effect is to increase the amount of iron in the blood, stimulate the appetite, augment the heart's beats and the bodily vigour. The secondary effects, which ensue sooner or later if the administration of iron is continued, are those which give the indications for homoeopathic prescribing. Hahnemann (Mat. Med. Pur.) describes the effects of iron on persons who habitually drink chalybeate waters: "In such localities there are few persons who can resist the noxious influence of the continued use of such waters and remain quite well, each being affected according to his peculiar nature. There we find more than anywhere else chronic affections of great gravity and peculiar character, even when the regimen is otherwise faultless. Weakness, almost amounting to paralysis of the whole body and of single parts, some kinds of violent limb pains, abdominal affections of various sorts, vomiting of food by day or by night, phthisical pulmonary ailments, often with blood spitting, deficient vital warmth, suppression of the menses, miscarriages, impotence in both sexes, sterility, jaundice, and many other rare cachexias are common occurrences." The digestive disorders set up by Iron are marked and peculiar, and among them is intolerance of eggs. The occurrence of this symptom in a patient about forty-five, who had had repeated attacks of articular rheumatism, led Kunkel to cure his case after he bad been dosed for three weeks with salicylate of soda by the allopaths. The only other distinctive feature was constant.< of pain after midnight. The obvious advantages derived in many cases of anaemia from the use of Iron in its crude forms has led to very grave abuses in old-school practice. That Iron is what may be called a "nutritive" remedy in certain defective blood conditions, having an organopathic relation to the blood, I have no doubt. In the anaemia of cancer and syphilis it is often of great service as an accessory, and need not interfere with more specific remedies. But it is not suited to all cases of anaemia and chlorosis, or even to a majority of them, and should never be given without discrimination and careful watching. But apart from its organopathic sphere, Ferrum has a strictly homoeopathic use in anaemia in which the highest potencies are curative. For excess of Iron will cause anaemia, and at times will aggravate it when present. The type of anaemia caused by Iron and suited for its homoeopathic use is commonly seen in young persons subject to irregular distributions of blood. The cheeks are flushed as if in blooming health; but in spite of bloom in appearances there is pallor of lips and mucous membranes, great fatigue and breathlessness, and any motion will set up the symptoms. Delicate girls, fearfully constipated, with low spirits. Chlorosis with erethism. Mucous membranes abnormally pale. Feet swell. The irregular distribution of blood in chlorotics recalls another set of symptoms which indicate Ferrum: haemorrhages of many kinds, from over-fulness of blood-vessels from vaso-motor paralysis, or else from delicacy of the vessels themselves. Throbbing pains, the blood-vessels all over the body throb violently. Feet swell. Fulness of blood-vessels accompanies neuralgia, which is brought on by washing in cold water, especially after being over-heated. Hammering headache. The pulse of Ferrum is full and yielding; (that of Acon. is full and bounding). With Ferrum there is excessive irritability, both of the mind and of the tissues. It is like Arsen. and Chin. in this, as in many other symptoms, and it is an antidote to both. It is one of the best remedies for over-dosing with quinine, and hence the favourite old-school combination of "Quinine and Iron" is so far a wise one. Cramps are well marked in the pathogenesis; irritability of the bladder causing incontinence of urine when standing; irritability of the bowels, causing diarrhoea whilst eating. This symptom is peculiar to Ferrum, the diarrhoea coming on when the patient begins to eat. Many remedies have it immediately after eating. < From eating eggs. There is also gastralgia, heavy pressure in region of stomach; a feeling as if something rolled into the throat and closed it like a valve; frequent spells of nausea, periodic vomiting (especially at twelve midnight). The liver and spleen are affected. Walls of abdomen are sore. Pain in os tincae on lying down; feeling of dryness in vagina. Ferrum is a remedy that should be given carefully in haemorrhagic phthisis, as it may aggravate. The acetate, iodide, and phosphate are better than the metal in such cases, unless the similarity is very close. Rheumatic symptoms, especially of left shoulder and deltoid. Paralytic weakness. Restlessness. Tremor. Most symptoms are < by motion, especially sudden motion. Vertigo on suddenly rising; when crossing a bridge over water; vertigo as if balancing to and fro, as when on water. Neuralgia is > moving slowly about. In fact "> moving about slowly" is a keynote condition of many Ferrum cases. Rest < cramps. Lying down < pain in face; asthma; = pain in os tincae; > cough (H. W., xxxi. 57). Descending stairs < headache. Walking slowly > palpitation; pain in arms; in hip-joint. The chief time of aggravation is night, and especially midnight, and also in early morning. The symptoms generally are < in cold weather, and > in warm air; but there is a good deal of contradictoriness in this respect, showing the irritability of Ferrum to all influences: uncovering chest > asthma and constriction, but too light covering < pain in shoulder. Over-heating = neuralgia, and so does washing in cold water. There is dread of open air, but open air > headache. The chlorosis of Ferrum is < in winter.