280 NEW ZEALAND NATURE-STUDY BOOK 
readily appreciate and understand. None of the minerals 
we have dealt with are either malleable or ductile—all 
the metals possess these properties in a greater or less 
degree. | 
TRON. 
Both the metal itself and specimens of Iron Ore should 
be available when dealing with these lessons. 
Wrought Iron. Examine a piece of Wrought Iron. 
Observe the general shape and colour of the specimen. 
Scrape away the brown coating from the surface and 
ascertain that Iron is a bright white metal. Examine 
the polished surface of some iron articles, ¢.g., knife-blade, 
scissors, fire-irons, and notice its bright shining lustre. 
Observe under similar conditions the lustre of other metals, 
and ascertain that they all have this shining appearance in 
a greater or less degree. Explain that this lustre is a 
special property of metals and is called metallic. Revert 
to the brown surface coating and elicit its name—rust. 
Draw attention to the conditions under which Iron rusts— 
viz., the presence of damp air—and explain the process— 
viz., the union of oxygen contained in the air or dissolved 
in water with the metal, forming an oxide of iron or rust. 
Kduce that the metal is opaque, tough and hard, and 
find its scale of hardness; or compare it in this connection 
with other substances examined. Notice that it (Wrought 
Iron) is without fracture, cleavage, crystalline form, 
taste, odour, and that it does not burn. 
Place a piece of Wrought Iron in a hot flame, and after 
allowing it to become heated quickly withdraw and hammer 
it ona suitable surface. Notice how soft it has become. 
Try the same operation with Iron which has not been 
heated. Iron becomes soft when heated, and can then be 
hammered out into thin sheets—it is malleable. Refer 
to iron wire and explain or educe that it can also be drawn 
