Tmolos when the gold deposits were being worked, especially since the gold that was found there was probably in the form of electrum which varied greatly in quality. This variation is shown by the composition of coins made of electrum that were minted during the seventh and sixth centuries b.c. in Lydia or the neighboring countries.337 Certainly some such method of assaying must have been necessary for the determination of the gold content of electrum and its value in relation to pure gold or pure silver.
48. Of such \inds are the special qualities and powers found in stones. Earth has fewer of these, though they are more peculiar; for it is possible for earth to be melted and softened and then hardened again.
The second part of the treatise, dealing with the various earths, begins here. In this context the verb τήκεσθαι really describes a softening caused by the action of water, and μαλάττεσθαι means a softening caused by die action of heat. Therefore τήκεσθαι does not refer to the melting of earths in the modern sense but rather to their disintegration by water. These two different ways of reducing solid bodies to an apparent or real state of fluidity are discussed at length by Aristotle,338 who makes clear by examples the special meanings usually attached to these two words in the scientific writings of the Peripatetic school. Moreover, the distinction that Theophrastus makes between earths and stones seems to be based on the philosophical views expressed by Aristotle about liquefaction and solidification. In general, it is based on the Aristotelian doctrine mentioned in section 3, that opposite effects are produced by opposite causes. Since earths were supposed to be formed by the action of fire alone (sec. 3), they could be disintegrated readily by the action of water, because water, the moistcold, was the direct opposite of fire, the dry-hot, and hence exercised the opposite effect on the same kind of matter.339 Earths could be disintegrated by water, since they were supposed to contain pores large enough to admit water particles, which could easily enter diem and cause disintegration.340 On the odier hand,
337 J. Hammer, Zeitschrift fur Numismatic, XXVI (1908), 17-51; W. Giesecke, Antik.es Geldwesen (Leipzig, 1938), pp. 16-83.
338 Meteorologica, IV, 6-9. 339 Op. cit., IV, 6, 383A. 340 Op. at., IV, 9, 385B.
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