n still alive) to discern the nature
of effused forms in the chapter on forms effused by spherical magneticks.
But if iron is injured somewhat by rust, it is affected either only
slightly or not at all by the stone. For the metal is spoiled when eaten
away and deformed by external injuries or by lapse of time (just as has
been said about the loadstone), and it loses its prime qualities which are
conjoined to its form; or, being worn out by age, retains them in a languid
and weak condition; indeed it cannot be properly re-formed, when it has
been corrupted. But a powerful and fresh loadstone attracts sound and clean
pieces of iron, and those pieces of iron (when they have conceived
strength) have a powerful attraction for other iron wires and iron nails,
not only one at a time, but even successively one behind another, three,
four or five, end to end, sticking and hanging in order like a chain. The
loadstone, however, would not attract the last one following in such a row,
if there were no nails between. [Illustration] A loadstone placed as at A
draws a nail or a bar B; similarly behind B it draws C; and after C, D. But
the nails B and C being removed, the loadstone A, if it remain at the same
distance, does not raise the nail D into the air. This occurs for this
reason: because in the case of a continuous row of nails the presence of
the loadstone A, besides its own powers, raises the magnetick natures of
the iron works B and C, and makes them, as it were, forces auxiliary to
itself. But B and C, like a continuous magnetical body, extend as far as
{71} D the forces by which D is taken and conformed, though they are weaker
than those which C receives from B. And those iron nails indeed from that
contact only, and from the presence of the loadstone even without contact,
acquire powers which they retain in their own bodies, as will be
demonstrated most clearly in the passage _on Direction_. For not only
whilst the stone is present does the iron assume these powers, and take
them, as it were, vicariously from the stone, as Themistius lays down in
his 8th book on Physicks[161]. The best iron, when it has been melted down
(such is steel), is allured by a loadstone from a greater distance, is
raised though of greater weight, is held more firmly, assumes stronger
powers than the common and less expensive, because it is cast from a better
ore or loadstone, imbued with better powers. But what is made from more
impure ore turns out w