Page:Encyclopædia Britannica, Ninth Edition, v. 13.djvu/375

I 11 N 359 In America, which comes next to Great Britain iu amount of pig iron production, and slightly exceeds that country in make of steel, the following figures illustrate the production of pig iron during the last twenty-five years (in thousands of tons of 2000 Ib each) : Anthracite. Charcoal. Bituminous. Total. 1854 339 342 54 736 1858 361 285 58 704 1862 470 187 131 788 1866 749 333 268 1350 1870 930 365 570 1865 1873 1313 578 978 2869 1876 795 309 990 2094 1879 1273 359 1439 3071 The following list of American iron and steel works is. abridged from the Directory of the Iron-Works of the United States, April 15, 1880 : ( Bituminous 203 Completed blast furnaces. March 1, 1880 ... ^Anthracite 2-28 (Charcoal 266 C97 ( Bituminous 23 Blast furnaces building, ,, < Anthracite 12 (Charcoal 9 44 Annual capacity of completed furnaces (in thousands of tons) C500 Completed rolling mills and steel works, March 1, 1880 382 Rolling mills building 10 Single puddling furnaces (double ones counting as two) 4467 Heating furnaces 2419 Trains of rolls 1397 Annual capacity of rolling mills (in thousands of tons) 4000 ,, rail mills 2150 Completed Bessemer steel works, March 1, 1880 (2 more building) .. 11 ,, converters ,, 10 82 Open hearth steel works 3 22 ,, furnaces 6 33 Crucible cast steel works 3 35 Forges for making iron direct from ore, March 1, 1880 . . 6!) ,, Bloomaires ,, ,, (1 more building) 59 Annual capacity (in thousands of tons)... -J uooiifaiix s 85 80 165 The present position of the iron and steel trade generally as compared with that at a period of some quarter of a century ago, may be put in a few sentences thus. An enormous increase in the production of iron and steel from natural sources has occurred ; not only have the older iron producing countries, as a rule, shared largely in this increase, but further, in many countries and districts where the amount of iron production was formerly little more than a nominal amount or even absolutely nil, the manufacture has now attained to notable dimensions, whilst there is every prospect of this increase in production continuing, notwithstanding the great fluctua tions in trade experienced from time to time in particular districts. This is mainly due to the vastly increased use of iron and steel (or so-called steel = fused iron of a low degree of carbonization) for constructive and other general purposes, and especially to the introduction of the peculiar melted products obtained from pig iron by means of Bessemer s blowing process conjoined with Mushet s spiegeleisen-addition improvement ; by Siemens s open- hearth "steel" making process involving the use of gaseous fuel and the regenerative principle ; or by various modifications of these methods, such as the Snelus-Thomas- Gilchrist process, by means of which phosphorus is removed to a large extent from the pig iron whilst undergoing de- carbonization. By this and various other allied devices, the production of useful kinds of so called " steels " from impure ores, which till recently could only be utilized for inferior cast and wrought iron production, has become possible. On the other hand the increasing use of fused " steels," prepared by various of these methods for many purposes for which wrought iron was exclusively used some quarter of a century ago, has stimulated the wrought iron department, and has in consequence caused the inven tion of numerous machines for diminishing the cost and increasing the output of puddled iron, and for effecting a greater degree of purification than hand puddling ordinarily produces. Notwithstanding these advances, however, it is evident that the weld iron industry is by no means increas ing in magnitude as rapidly as the ingot metal manufacture. So evident, is the disparity that it is believed by many competent judges that puddled metal will in a longer or shorter time become practically a thing of the past, and that ingot metal will almost wholly take its place, especially when the advantages of the latter as regards physical qualities and cheapness of production have become more extensively appreciated. (c. E. A. w.) IRON, THERAPEUTIC USES OF. The use of iron in the cure of disease dates from a very early period. Pliny speaks of its medicinal effects, and there is reason for believing that it was administered several centuries before his time. But Sydenham was the first to point out its most important therapeutic property, its blood-restoring power. " To the worn out and languid blood," he says, "it gives a spur or fillip whereby the animal spirits which before lay prostrate or sunk under their own weight are roused and excited." The blood is composed of a fluid wherein float roundish red bodies, the blood corpuscles, which play a leading part in those tissue changes essential to life. Each corpuscle consists of a stroma permeated by a red fluid, haemoglobin, which has the remarkable property of readily combining with either oxygen or carbonic acid, but so loosely that under slightly altered conditions these gases are as readily separated from it. In the lungs the corpuscles, through their haemoglobin, take up oxygen which they carry to all parts of the body. But in the presence of the vital pro cesses of disintegration and repair constantly going on in the tissues, the corpuscles yield up the oxygen they have brought, and supply an element necessary for these pro cesses. Having got rid of the oxygen, the haemoglobin then unites with the carbonic acid produced by tissue disinte gration, and the corpuscles thus reladen carry their burden back to the lungs, and discharge there the carbonic acid, taking up anew a supply of oxygen. If the haemoglobin of the blood fall below a certain standard, the supply of oxygen necessary to healthy tissue changes in brain, nerve, muscle, &c., becomes too limited, and the changes will be imperfectly performed; hence defective vitality, general or local. Now the ingestion of iron increases the luemo- globin supply when it is defective ; it promotes the pro duction of blood corpuscles, and causes each corpuscle to carry with it more haemoglobin ; hence the health-giving power possessed by this metal. The exact method in which the increase in red colouring matter is brought about we do not know, but in the fact that iron forms an essential constituent of haemoglobin we have some clue to its utility. Anaemia or spanaemia is the name given to that condition in which the red colouring matter of the blood is below the normal amount. It is indicated by pallor of skin and mucous membranes, and by a depressed condition of brain, of muscle, and of the tissues generally. A beating headache is often present, sustained mental or physical exertion is difficult, palpitation and breathlessness are sources of in convenience ; in the female the uterine functions are often in abeyance. By a chalybeate course we can usually restore to the blood its due supply of haemoglobin, and cause the gradual disappearance of all these symptoms. It would be impossible Lere to enumerate all the special forms of spannunia in which iron is prescribed. It will be sufficient to point