don Press,
1865, vol. 1, p. 157)

[42] Francis Bacon, _De augmentis scientiarum_, bk. 3, ch. 4,
in _Works_, ed. J. Spedding, R. L. Ellis, and D. D. Heath,
Boston, n.d. (1900?), vol. 2, p. 267.

[43] _The poems of John Donne_, ed. H. J. C. Grierson,
London, Oxford University Press, 1933, p. 175 ("To the
Countesse of Bedford, On New Yeares Day").

[44] M: pp. 33, 34.

[45] M: pp. 34, 35. Aristotle, _Works_, ed. W. D. Ross,
Oxford, 1908--1952, vol. 2, _De generatione et corruptione_,
translated by H. H. Joachim, 1930, vol. 3, _Meteorologica_,
translated by E. W. Webster, 1931.

[46] M: pp. 34, 35, 64, 65, 69, 81. Dr. H. Guerlac has kindly
brought to my attention the similarity between the
explanation given in Gilbert and that given in the
_Meteorologica_, bk. 3, ch. 6. p. 378.

[47] M: p. 83.

[48] A statement of the relation between Aristotle's four
elements and place can be found in Maier, _op. cit._
(footnote 17), pp. 143-182.

According to Gilbert the primary source of matter is the interior of
the earth, where exhalations and "spiritus" arise from the bowels of
the earth and condense in the earth's veins.[49] If the condensations,
or humors, are homogeneous, they constitute the "materia prima" of
metals.[50] From this "materia prima," various metals may be
produced,[51] according to the particular humor and the specificating
nature of the place of condensation.[52] The purest condensation is
iron: "In iron is earth in its true and genuine nature."[53] In other
metals, we have instead of earth, "condensed and fixed salts, which
are efflorescences of the earth."[54] If the condensed exhalation is
mixed in the vein with foreign earths already present, it forms ores
that must be smelted to free the original metal from dross by
fire.[55] If these exhalations should happen to pass into the open
air, instead of being condensed in the earth, they may return to the
earth in a (meteoric) shower of iron.[56]

[49] M: pp. 21, 34, 35, 36, 45.

[50] M: pp. 35, 36, 38, 69; see, however, pp. 42-43: "Iron
ore, therefore, as also manufactured iron, is a metal
slightly different from the homogenic telluric body because
of the metallic humor it has imbibed ..."

[51] M: pp. 19, 34, 36, 37, 42, 69.

[52] M: pp. 35, 36, 37, 38.

[53] M: pp. 38, 63, 69, 84; on p. 34 he says that iron is
"more truly the chil