Iron.

Syn. Fer (F.), Ferro (I.), Eissen (G.), Yzer (Dutch), Jem (Dan. Swed.), Ferro (Portug.), Zelaco (Polish), Hierro (S.), Loha (H. Duk. Sam.), Ayas (San.), Sow-ik (Esquimaux), Sheljeso (Russian), Eerumboo (Tarn.), Ahun (Pers.), Hedeed (Arab.), Bessee (Malay), Yakada (Cyng.).

threaten to make me sneeze to death, and the touching of the milk with my fingers excoriated them as if scalde with boiling water."-Appendix, 4to. p. 43. I Annates de Chimic, lxviii. 44.

This metal is one of the most abundant metallic productions of nature. Its ores are found in almost every part of the globe, but that of Sweden is most esteemed. It is also contained in the soil; often in the water; and as a constituent of vegetable and animal bodies. Iron is procured,

A. In its metallic state: i Alloyed with lead and copper. Sp. 1. Nativeiron.

---------with nickel. 2. Meteoric Iron masses.

ii. Sulphureted. 1. Iron pyrites. Van a. Common.

b. Radiated.

c. Hepatic.

d. Capillary.

e. Cellular. 2. Magnetic pyrites.

B. United with oxygen : iii. Oxidized. 1. Magnetic iron stone. Var. a. Common.

b. Iron sand.

2. Spicular iron ore. Var. a. Common.

b. Micaceous.

3. Red iron stone. Var. a. Red scaly iron ore.

b. Red ochre.

c. Compact.

d. Red haematite.

4. Hydrate of iron. Var. a. Brown haematite.

b. Compact hydrate.

c. Globular hydrate.

d. Ochrey brown iron stone.

e. Bog iron ore. C Acidified:

5. Hydrate of iron and manganese. iv. Salts. 1. Carbonate. Var. a. Sparry iron ore.

b. Com. clay iron ore.

2. Phosphate. Var. a. Phosphate of iron.

b. Blue iron earth.

3. Arseniate of iron.

4. Chrornate of iron.

5. Silicate.

6. Tungstate.

7. Sulphate. Var. a. Pitchy iron ore.

Metallic iron can be extracted from all of these ores, but the oxides are those more commonly wrought; and, in this country, the argillaceous ironstone and the red haematite are the kinds in general use. The process varies in different places, but the principles on which it is conducted are every where the same. The ore is first roasted by placing it, after it is broken into small pieces, in alternate strata with small coal and lime, either in a kiln, or built up in a pyramidal form on the ground, and setting fire to the lowest stratum of coal. The lime acts as a flux, and forms with the impurities of the ore a fusible slag. This part of the process expels any sulphur, water, or carbonic acid, with which the ore may be combined; and it is then smelted with coke in a conical furnace of the strongest masonry; the heat being raised to a very high degree by passing a blast of condensed air through the furnace; and to facilitate the separation of the melted metal, lime is used as a flux. The scoria or slags are drawn out through an opening towards the bottom of the furnace; and the melted metal, which is collected in a cavity at the bottom, is run off into moulds.

In this state it is called pig, or cast iron; and requires to be again fused and submitted to the action of the hammer, or passed between rollers, before it is sufficiently pure either for the majority of the purposes of art or of medicine.1

Pure forged or bar iron is of a bluish white or grey colour, of a fibrous texture, and very brilliant in the fracture. It emits a peculiar odour when rubbed, and has a styptic taste. Its specific gravity varies from 7.6 to 7.8. It is attracted by the magnet, and becomes magnetic; properties which distinguish it from all other metals. It is very malleable, but less so than gold, silver, or copper; and is more ductile, tenacious, and elastic, than any other metal.2 Iron can be ignited by percussion, and melts at 158° of Wedgwood. Its surface is soon tarnished and oxidized when exposed to the air; and the oxidizement is much hastened by the presence of water, which it decomposes.8 Percussion at a high temperature separates from its surface oxidized scales; the sparks produced by its collision with flint are oxidized; and in the state of wire, when made red hot at one extremity, and introduced into a bottle of pure oxygen gas, it burns with great splendour, and is oxidized in globules. The equivalent of iron is 28.

Iron is of all the metals the least injurious to the animal system, being in no respect poisonous, even when rendered active by oxygen. It was medicinally used by the ancients; for Dioscorides, we know, employed it quenched in wine as a remedy for dysentery; and its use was by no means unfre-quent as an external application for the cure of malignant ulcers. The effects of iron, or rather its oxides, however, as an internal remedy, were very little understood until more modern times. It acts as a powerful tonic, increasing the general excitement, promoting the digestive powers and healthy secretions, giving a more florid hue to the blood, and augmenting in a great degree the energy of the muscular fibres. It answers the intentions for which it is prescribed more effectually when it is given in small doses, minutely divided, as it is found in chalybeate springs, and its use long continued. The diseases in which it is used are those which are dependent on, or attended with a weak, languid, leuco-phlegmatic habit of body, as chlorosis, hysteria, dyspepsia, fluor albus, gleet, passive haemorrhages, palsy, scrofula, rickets, and the last stage of phthisical affections; it is also beneficial in convalescence from almost all acute diseases, and has been lately recommended as a specific in cancer.

The use of iron is contra-indicated whenever the inflammatory diathesis prevails, or there is any particular fulness of the vessels; or an increased secretion of bile, particularly in sanguineous habits. In these states of the system it occasions heat, thirst, headach, laborious respiration, and many other unpleasant symptoms; but when in a proper state of the body, few medicines are capable of producing more beneficial effects.

1 The mines of the Lower Harz yield annually 14,000 tons of ore.

2 A square inch of iron wire requires 113,000 lbs. avoirdupois to pull it asunder: the same quantity of copper wire requires 61,000: of platinum wire 56,000: silver wire 40,000; and gold wire 31,000.

3 When iron exposed to a moist atmosphere rusts, a protocarbonate is first formed; by degrees the protoxide passes into the hydrated peroxide, and the carbonic acid is evolved; a simple oxide combined with some ammonia remains.

For the purposes of medicine, soft malleable iron undergoes various preparations (see Preparations and Compositions): but at present we have to notice it only as it is mentioned in the lists of materia medica of the British Pharmacopoeias.

1. Metallic Iron.

Officinal. Ferrum, Lond. Fila et Limatura, Edin. Ferri fila, scobs, Dub. Iron filings and wire.

Syn. Limailles de Fer(F.), Gopulvertes Eissen (G.), Limatura di Ferro(I.), Limadura de Hierro (S.), Cerumboo podie ( Tarn.), Sow-ik (Esquimaux).

These filings are obtained from the workers in iron; but, as they are often mixed with copper and brass filings and other impurities, it is necessary, in order to purify them, to draw them upwards through a sieve or piece of coarse gauze, with a magnet.