The gas-producer, of which there are commonly four in a block, is a rectangular chamber with a sloping front and grate of firebars, on which, by means of a feeder, a thick layer of fuel is maintained. This fuel is mainly converted into carbonic oxide, hydrogen, and hydrocarbons—all combustible gases—and together forming the '•gas" we have referred to in describing the regenerator. Almost any kind of fuel, however poor, may be used for these gas-producers,which are connected by means of a pipe with the generators.
3. Iron in its Physiological and Therapeutic Relations. —Iron is an essential constituent of the coloring matter of the blood-corpuscles of all vertebrate animals; and according to the best authorities, one part by weight of iron is found in 230 parts of blood-corpus cles, and the total quantity of this metal in the blood of a man weighing 140 pounds is about 38 grains. It is the presence of iron in the blood that communicates to the ashes of that fluid their reddish-brown color, the iron being found in them, as the peroxide. The ashes of the hair, of birds' feathers, of the contents of eggs, of the gastric juice, of milk, and indeed of most animal fluids contain traces of this metal.
Nothing is known with certainty regarding the chemical condition of the iron in the animal body, that is to say, whether it is present as a protoxide, a peroxide, etc. It is introduced into the system with the food and drink, and any excess beyond what is required is discharged with the excrements. When an insufficient quantity is contained in the nutriment, chalybeate medicines become necessary. The iron that is set free within the system by the constant disintegration of blood-corpuscles is carried out of the system partly by the urine, partly by the coloring matter of the bile, which is highly ferruginous, and probably is in part eliminated by the hair. The exact part which the iron plays in the body is uncertain; but it is most probable that the power whichthe blood corpuscles possess as oxygen carriers is mainly due to the presence of this substance.
When from any cause the blood-corpuscles are reduced in number, the state known as anemia (q.v.) is produced, which is accompanied by general weakness and deranged functions. In this condition of the system the iron compounds are of incomparably more service than any other remedies. In chlorosis (q,v.), which is closely allied to
anwmia, in amenorrhoea; and in certain painful nervous affections, the salts of iron are of especial service. The forms in which iron may be prescribed are very numerous, and vary considerably in their utility, according to the readiness with which they get taken up into the blood. Amongst the most generally used ferruginous medicines may be mentioned the tincture of tho sesquichloride, the saccharine carbonate, the compound iron mixture (containing the carbonate), the sulphate, the potassio-tart rate, several citrates (especially the citrate of iron and quinine), etc. A course of chalybeate waters (q.v.) may often be prescribed with great advantage, when the patient cannot bear the admin istration of iron in its ordinary medicinal form. .
IRON (ante). The processes of converting the ore into metallic iron are of two kinds— direct and indirect. In the direct process the ore is converted by one operation or a few operations into wrought iron. This method, employed by the ancients, is still used iu some parts of the world, as in India and Central Asia, Africa, and South America. With some modifications and improvements it is practiced also in Europe and the United States, and yields the best iron, but at a greater expense than by the indirect process, which consists in first making pig-iron by smelting the ore in a blast-furnace with fluxes, by which means the metal is more readily obtained, and then reducing the by puddling and other processes, or by certain manipulations converting the pig-iron into cast-steel.
The following table, taken with the preceding from the annual report of the secre tary of the American Iron and Steel Association, presented May 20, 1880, shows in tons of 2,000 lbs. the production of all kinds of iron and steel iu the United States from 1872 to 1879: IRON,.a co. in s.c. Missouri; bounded n.e. by Iron mountain and Pilot Knob; 500 sq.m.; pop. '70, 6,278. It is mountainous. and has extensive forests of oak, pine, wal nut, etc. Iron ore is abundant, and gold, lead, nickel, and other metals are found. The staple products aregrain and wool. The St. Louis and Iron Mountain railroad K passes through it. Pilot Knob is in this county, a conical hill 1500 ft. above the sea, and 560 ft. above the plain.