The Romance of Modern Chemistry
Forfatter: James C. Phillip
År: 1912
Forlag: Seeley, Service & Co. Limited
Sted: London
Sider: 347
UDK: 540 Phi
A Description in non-technical Language of the diverse and wonderful ways in which chemical forces are at work and of their manifold application in modern life.
With 29 illustrations & 15 diagrams.
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CHAPTER VII
WHERE TWO METALS ARE BETTER THAN ONE
IN the foregoing chapter we have had illustrations of
the differences exhibited by metals in regard to
specific gravity and fusibility, but there are, of course,
many other properties—hardness, malleability, ductility,
and the like—which have to be taken into account when
we are considering the suitability of a given metal for
a certain purpose. Frequently it happens that the metal
is suitable for the purpose in all respects save one, in
which case it may be possible to correct the deficiency
by adding another metal, provided at the same time that
this second constituent does not detract from the valuable
properties of the first. The effect of the presence of
carbon in iron might be considered as an illustration of
this principle, but carbon is not a metal, and the amount
present is not great, so that wrought-iron, cast-iron, and
steel are rather in a class by themselves.
We may make good the deficiencies of a metal by the
addition of another in more than one way. It is not
always necessary actually to mix the metals; we may
put one on the top of the other, as in tinplate or
galvanised iron. In regard to strength, durability, and
cheapness, iron is an excellent material, but the weak
feature about it is its liability to corrode when exposed
to a moist atmosphere: it rusts.
Articles made of iron which have to be exposed to air
72