es or points of variation; then they also lead along and turn round
more quickly, according to the greater quantity and mass of wood, a boat
and other stuff. In a declination instrument, the more powerful force of a
loadstone is looked for and required. Those therefore are more lively when
they get through their work readily, and pass through and come back again
with speed, and swiftly at length settle at their own point. Languid and
effete ones move more sluggishly[186], settle more tardily, adhaere more
uncertainly, and are easily disturbed from their possession.

* * * * *

{109} CHAP. XXXVII.

Use of a Loadstone as it affects
_iron._

By magnetick coition we test iron ore in a blacksmith's forge. It is burnt,
broken in pieces, washed and dried, in which way it lays down its alien
humours; in the bits collected from the washing is placed a loadstone,
which attracts the iron dust to itself; this, being brushed off with
feathers, is received in a crucible, and the loadstone is again placed in
the bits collected from the washing, and the dust wiped off, as long as any
remains which it will attract to itself. This is then heated in the
crucible along with _sal nitri_[187] until it is liquid, and from this a
small mass of iron is cast. But if the loadstone draws the dust to itself
quickly and readily, we conjecture that the iron ore is rich; if slowly,
poor; if it seems altogether to reject it, there is very little iron in it
or none at all. In like manner iron dust can be separated from another
metal. Many tricks there are also, when iron is secretly applied to lighter
bodies, and, being attracted by the motion of a loadstone which is kept out
of sight, causes movements which are amazing to those who do not know the
cause. Very many such indeed every ingenious mechanician will perform by
sleight of hand, as if by incantations and jugglery[188].

* * * * *

CHAP. XXXVIII.

On Cases of Attraction in other Bodies.

Very often the herd of philosophizers and plagiarists repeat from the
records of others in natural philosophy opinions and errors about the
attractions of various bodies; as that Diamond attracts iron, and snatches
it away from a magnet; that there are various kinds or magnets, some which
attract gold, others silver, brass, lead; even some which attract flesh,
water, fishes. The flame of sulphur is said to seek iron and stones; so
white na