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so it will not reach the sun. But at the side of the sun, it is

possible for the mirror to be at such an interval that the sun does

not dissolve the cloud, and yet sight reaches it undiminished

because it moves close to the earth and is not dissipated in the

immensity of space. It cannot subsist below the sun because close to

the earth the sun's rays would dissolve it, but if it were high up and

the sun in the middle of the heavens, sight would be dissipated.

Indeed, even by the side of the sun, it is not found when the sun is

in the middle of the sky, for then the line of vision is not close

to the earth, and so but little sight reaches the mirror and the

reflection from it is altogether feeble.

Some account has now been given of the effects of the secretion

above the surface of the earth; we must go on to describe its

operations below, when it is shut up in the parts of the earth.

Just as its twofold nature gives rise to various effects in the

upper region, so here it causes two varieties of bodies. We maintain

that there are two exhalations, one vaporous the other smoky, and

there correspond two kinds of bodies that originate in the earth,

'fossiles' and metals. The heat of the dry exhalation is the cause

of all 'fossiles'. Such are the kinds of stones that cannot be melted,

and realgar, and ochre, and ruddle, and sulphur, and the other

things of that kind, most 'fossiles' being either coloured lye or,

like cinnabar, a stone compounded of it. The vaporous exhalation is

the cause of all metals, those bodies which are either fusible or

malleable such as iron, copper, gold. All these originate from the

imprisonment of the vaporous exhalation in the earth, and especially

in stones. Their dryness compresses it, and it congeals just as dew or

hoar-frost does when it has been separated off, though in the

present case the metals are generated before that segregation

occurs. Hence, they are water in a sense, and in a sense not. Their

matter was that which might have become water, but it can no longer do

so: nor are they, like savours, due to a qualitative change in

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