IRON AND ITS ORES. Of all the metals iron is the most widely diffused, the most abundant, and the most useful. It is found not only intermixed with soils, and contained in rocks and minerals, but it is even met with in some animal and vegetable bodies, and also in mineral waters. It occurs rarely in nature in the metallic state, for almost the whole of it that has been found occurs as meteoric iron containing nickel, or in meteoric stones. It is mostly found either combined with oxygen, oxygen and carbonic acid, or sulphur. The best iron ores are oxides, which occur in pri mitive conntries, where they generally form very large beds ; such are those of Sweden : hut the greater part of the iron ore of Britain is an impure carbonate.
When separated from its ores, the colour of iron is grayish white with a tint of blue. It is extremely ductile, so that it maybe drawn into wire finer than the human hair, but it cannot be beaten into very thin leaves. It is of all metals the most tenacious, for a wire of an inch in diameter is capable of supporting a weight of about 550 lbs. It is susceptible of a high polish. It is combustible when minutely divided, as in the state of filings. It is very hard at common temperatures, and this pro perty may be increased by its being heated and then suddenly cooled; it then however becomes brittle. It requires a most intense heat to melt it ; but when heated to redness it becomes soft and pliable, and possesses the valuable property of welding, that is, two pieces of red•ot iron may be made to unite by ham mering. Its texture is fibrous. Its specific gravity is about 7.77 ; but this varies in some degree according to the extent to which it has been drawn, rolled, or hammered, and it is , increased by fusion. Iron, or rather steel, is capable of being rendered permanently mag netie. Iron has great affinity for oxygen and sulphur, and some other elementary bodies, and combines with them in various propor tions.
The chief ores of iron are the following :— Oryffulous or Magnetic ; Specular or Jifica cam., ; Goethite ; Iron Froth ; Red Hematite ; Brown Hematite ; Carbonate of Iron, or Spa those Iron Ore ; and Clay Iron Stone. The
last named is the most abundant in this country.
Of the valuable chemical substances in which iron forma an ingredient, it is difficult to give even a list: so numerous and varied are they. Steel and black lead consist of iron and carbon ; green vitriol is sulphate of iron. The presence of phosphorus in iron is said to give it what iron manufacturers call the cold short quality. The acetate of iron is much used in calico printing.
The Alloys of Iran arc much less useful than might bo expected from the extreme utility of the metal itself. Potassium and iron, and sodium and iron, combine when heat is applied to them : the alloys are more fusible than pure iron, especially when in contact with the air; and they are decomposed by air and water. Siliciunt and iron form an alloy which is ductile or brittle according to the quantity of charcoal which it contains. Arsenic and iron form en alloy which has a grayish white colour, does not obey the magnet, is very brittle, and much more fusible than iron. Chromium and iron form an alloy very little known. With columbium a hard brown alloy is formed. Zinc gives a white and brittle alloy with iron. Tin and iron form the alloy seen on tin-plate ware. Antimony and iron unite when heated together in close vessels : the alloy is white, hard, brittle, and its specific gravity is less than that of the mean of the two metals. No metal appears to deprive iron more of its magnetic property than antimony. Cobalt and iron form a hard magnetic alloy. Nickel and iron form the meteoric alloy. Bis muth combines with difficulty with iron. Mo lybdenum forms with it a blueish gray brittle alloy. The alloy of copper and iron is mag netic. Silver combines readily with iron when they are fused together, but they separate on solidification, and globules of silver appear on the surface of the alloy. With mercury a white tenacious alloy is formed. Lead and iron com bine with difficulty. Rhodium, iridium, tung sten, and platinum may all be made to form alloys with iron. Gold and iron combine with facility; a compound of eleven parts of gold and one part of iron is nearly white, and very ductile.