which hold two of these pots, are divided into three parts ; the lowest part is a
foot high, and has an opening at the front for the draught ; the top of this is
covered with iron plates, which are perforated near the edges, and these
support iron rods, upon which the firewood is placed. The middle part of the
furnace is one and a half feet high, and has a mouth in front, so that the wood
may be inserted ; the top of this has rods, upon which the bottom of the pots
stand. The upper part is about two feet high, and the pots are also two feet
high and one digit thick ; these have below their mouths a long, slender spout.
In order that the mouth of the pot may be covered, an earthenware lid is
made which fits into it. For every two of these pots there must be one pot
like product. The equipment described for pyrites in the next paragraph would be obviously
useful only for coarse material.
But little can be said on the history of sulphur ; it is mentioned often enough in the Bible
and also by Homer (Od. χχιι., 481). The Greeks apparently knew how to refine it, although
neither Dioscorides nor Pliny specifically describes such an operation. Agricola says (De
Nat. Fos., 220) : " Sulphur is of two kinds ; the mineral, which the Latins call vivum, and
the Greeks apyron, which means ' not exposed to the fire ' (ignem non expertum) as
rightly interpreted by Celsius ; and the artificial, called by the Greeks pepyromenon, that
is, ' exposed to the fire.' " In Book X., the expression sulfur ignem non expertum frequently
appears, no doubt in Agricola's mind for native sulphur, although it is quite possible that
the Greek distinction was between " flowers " of sulphur and the " wax-like " variety.
