other sand, and scattered far and wide in different directions, or they
sink down into the depths of the sea. For the same reasons, the sands of
lakes can very rarely be washed successfully, even though the streams rising
from the mountains pour their whole volume of water into them. The
particles of metals and gems from the springs are very rarely carried into the
marshes, which are generally in level and open places. Therefore, the
miner, in the first place, washes the sand of the spring, then of the stream
which flows from it, then finally, that of the river into which the stream
discharges. It is not worth the trouble to wash the sands of a large
river which is on a level plain at a distance from the mountains. Where
several springs carrying metals discharge their waters into one river, there
is more hope of productive results from washing. The miner does not
neglect even the sands of the streams in which excavated ores have been
washed.
The waters of springs taste according to the juice they contain, and
they differ greatly in this respect. There are six kinds of these tastes which
the worker14 especially observes and examines; there is the salty kind,
which shows that salt may be obtained by evaporation ; the nitrous, which
indicates soda ; the aluminous kind, which indicates alum ; the vitrioline,
which indicates vitriol ; the sulphurous kind, which indicates sulphur ;
and as for the bituminous juice, out of which bitumen is melted down, the
colour itself proclaims it to the worker who is evaporating it. The seawater however, is similar to that of salt springs, and may be drawn into
low-lying pits, and, evaporated by the heat of the sun, changes of
itself into salt ; similarly the water of some salt-lakes turns to salt when dried
by the heat of summer. Therefore an industrious and diligent man observes
and makes use of these things and thus contributes something to the
common welfare.
The strength of the sea condenses the liquid bitumen which fìows into
it from hidden springs, into amber and jet, as I have described already in
my books " De Suhterraneorum Ortu et Causis "15. The sea, with certain
"Excodor,—literally, " Smelter " or " Metallurgist."
"This reference should be to the De Natura Fossilium (p. 230), although there is a short
reference to the matter in De Ortu et Causis (p. 59). Agricola maintained that not only were
jet and amber varieties of bitumen, but also coal and camphor and obsidian. As jet
(gagates) is but a compact variety of coal, the ancient knowledge of this substance has more
interest than would otherwise attach to the gem, especially as some materials described in this
connection were no doubt coal. The Greeks often refer to a series of substances which burned,
contained earth, and which no doubt comprised coal. Such substances are mentioned by
Aristotle (De Mirabilibus. 33, 41, 125), Nicander (Theriaca. 3y), and others, previous to
the 2nd Century b.c., but the most ample description is that of Theophrastus (23-28) : "Some
" of the more brittle stones there also are, which become as it were burning coals when put into
" a fire, and continue so a long time ; of this kind are those about Bena, found in mines and
" washed down by the torrents, for they will take fire on burning coals being thrown on them,
" and will continue burning as long as anyone blows them ; afterward they will deaden, and
" may after that be made to burn again. They are therefore of long continuance, but their
" smell is troublesome and disagreeable. That also which is called the spinus, is found in
" mines. This stone, cut in pieces and thrown together in a heap, exposed to the sun, burns ;
" and that the more, if it be moistened or sprinkled with water (a pyritiferous shale ?). But
" the Lipara stone empties itself, as it were, in burning, and becomes like the pumice,
" changing at once both its colour and density ; for before burning it is black, smooth, and
" compact. This stone is found in the Pumices, separately in different places, as it were, in
