282 NEW ZEALAND NATURE-STUDY BOOK 
kitchen utensils, pipes used for drainage. What kind of 
Iron are horseshoes made of 1 Why ? ef: 
Steel. Procure an old saw. Shew that it bends, and 
moreover that when the bending force is withdrawn it 
springs back to its former position. Test a knitting needle 
and a piece of the mainspring of a clock in the same way, 
and educe that whereas Wrought Iron is flexible, Steel is 
elastic. Test for hardness and ascertain that Steel is 
harder than either of the other kinds of Iron. Notice that 
there are degrees of hardness in Steel—clearly the file used 
in sharpening a saw is harder than the metal of the saw 
which is rasped away. Contrast the surface of a knife- 
blade or a pair of scissors with that of some article made 
of Cast or Wrought Iron, and observe that Steel takes a 
better polish than either of the other two. 
Uses. Educe the uses of Steel. It is hard, elastic, and 
capable of being tempered to suit the purposes for which 
it is employed. All edge-tools or cutting instruments are 
made of Steel. It is also immensely strong, and hence is 
employed where strength and elasticity are essential, ¢9., 
for making ships, bridges, and wire ropes. 
Manufacture of Cast Iron. Iron is made from Iron 
Ore, an earthy mineral found in large quantities in many 
countries. The ores employed are either haematite (one 
of the oxides of iron), or clay-ironstone, an impure 
argillaceous (clayey) Carbonate of Iron. 
Roasting. The Ore is broken up, mixed with Coal 
and built into small heaps, which are kindled and allowed 
to smoulder for some time. During the process, which is 
known as roasting, the Ore loses about one-fourth of its 
weight. | 
Smelting. The roasted Ore is then mixed with about 
one-third of its weight of Quick-lime or Limestone, and 
almost its own weight of Coal, and emptied into a 
