Chapter XLVII: Book I: chap. xiii. Smelted iron has in itself fixed north and

south parts, magnetic activity, verticity, and fixed vertices or
poles.

Book II. chap. ii. Not only do amber and jet attract light
substances: the same is done by the diamond....

Book II. chap. ii. When the atmosphere is very cold and clear,
the electrical effluvia of the earth offer less impediment.

Book II. chap. xxv. A strong, large, loadstone increases the
power of another loadstone, and also the power of iron.

Book II. chap, xxxiv. Why a loadstone is of different power in
its poles as well in the north as in the south regions (two
experiments).

Book III. chap. xii. Iron becomes magnetized when red-hot and
hammered in the magnetic meridian; also when the iron bars have,
for a long time, lain fixed likewise in the north and south
position (two experiments).