passage in the back wall supporting the pan leads off the products of
combustion and the hot air into a short flue, sloping upwards, and
ending in a short vertical chimney. At the lower part some iron kettles
are placed in the flue for the purpose of heating the lye before it is
ladled into the evaporating pan.

With reference to the pan, it is made in a way that requires a great
deal of skill and practice. In the first place, beams reaching from the
one side to the other are laid on the top of the furnace walls, and are
covered with wooden boards, forming a temporary floor. Two or three feet
above this floor a strong horizontal network of poles of wood sustains a
number of straw ropes, with iron hooks hanging down, and of such a
length that the hooks nearly touch the wooden floor. The floor is
thereupon covered with a mixture of clay and small stones, 4 to 5 inches
thick, the workman being careful to incrustate the iron hooks into this
material. It is allowed to dry gradually, and when considered
sufficiently hardened, the wooden beams and flooring are removed with
the necessary precautions. The bottom of the pan remains suspended by
means of the ropes. The open spaces left all round between the bottom
and the top of the furnace walls are then filled up, and the border of
the pan, 9 inches to 10 inches high, is made of a similar mixture. It is
said that this extraordinary construction lasts from 40 to 50 days when
well made, and that it can be filled 16 times in 24 hours, with an
average of 500 litres of concentrated lye at each filling; but the
quantity depends upon the weather, and is less in winter than in summer.
During the cold season one pan yields 140 litres (of salt) each time it
is filled, and in the hot season from 190 to 210 litres. The average
consumpt of fuel is said to be 1500 kilos. in 24 hours.

In Persia, near Ballakhan, salt is still made, and has been made from