ower to do the same as the
stone; to wit, draw other rings, so that sometimes a long chain of iron
objects, nails or rings is formed, some hanging from others. The best iron
(like that which is called _acies_ from its use, or _chalybs_ from the
country of the Chalybes) is best and strongly drawn by a powerful
loadstone; whereas the less good sort, which is impure, rusty, and not
thoroughly purged from dross, and not wrought in second furnaces, is more
feebly drawn; and yet more weakly when covered and defiled with thick,
greasy, and sluggish humours. It also draws ores of iron, those that are
rich and of iron colour; the poorer and not so productive ores it does not
attract, except they be prepared with some art. A loadstone loses some
attractive virtue, and, as it were, pines away with age, if exposed too
long to the open air instead of being laid in a case with filings or scales
of iron. Whence it should be buried in such materials; for there is nothing
that plainly resists this exhaustless virtue which does not destroy the
form of the body, or corrode it; not even if a thousand adamants were
conjoined. Nor do I consider that there is any such thing as the
Theamedes[69], or that it has a power opposite to that of the loadstone.
Although Pliny, that eminent man and prince of compilers (for it is what
others had seen and discovered, not always or mainly his own observations,
that he has handed down to posterity) has copied from others the fable now
made familiar by repetition: That in India there are two mountains near the
river Indus; the nature of one being to hold fast all that is iron, for it
consists of loadstone; the other's nature being to repel it, for it
consists of the Theamedes. Thus if one had iron nails in one's boots, one
could not tear away one's foot on the one mountain, nor stand still on the
other. Albertus Magnus writes that a loadstone had been found in his day
which with one part drew to itself iron, and repelled it with its other
end; but Albertus observed the facts badly; for every loadstone attracts
with one end iron that has been touched with a loadstone, and drives it
away with the other; and draws iron that been touched with a loadstone more
powerfully than iron that has not been so touched.

* * * * *

{19} CHAP. VII.

What Iron is, and of what substance,
_and its uses._

For that now we have declared the origin and nature of the loadstone, we
think it nec