,,, - , —
à
II
nm
3!é
224 M O D E O F E V A P O R A T IO N .
could not repay the expence of evaporating
by fuel, in any country. The water of the
north sea contains 2^ per cent, of salt, and
yet it has never been attempted, that I know
of, to make salt from it by evaporation
with coal fires, even on the coast of Northumberland
or Durham, where refuse coal,
suited to the purpose, might be purchased
for D. 6d. per ton. In order to make salt
from the saline water at Moutiers, it was
necessary to concentrate it by natural evaporation
; and to effect this speedily, it was
required to spread the surface of the fluid
over as large a space as possible, the ratio
of evaporation being, ceteris paribus, in
proportion to the extent of the surface exposed
to the action of the atmosphere.
The first attempt at Moutiers was made in
1550, by arranging pyramids of rye-straw
in open galleries, and letting the water
trickle through it gradually and repeatedly.
By this process a portion of the sulphat of
lime it contained was deposited on the
straw, and the water became concentrated
to a certain degree. It was then carried to
the boiler, and further evaporated by fuel.
In 1730 the present buildings were erected
by order of Charles Emanuel the third.
E V A P O R A T IN G H O U S E S . 225
There are four evaporating houses, called
Maisons d’Epines (literally, houses of
thorns). Nos. 1. and 2. receive the water
from the reservoir, and concentrate it to
about three degrees of strength, viz. they
evaporate one half of the water they receive.
These houses of evaporation are 350 yards
in length each, about 25 feet in height, and
seven feet wide. They are uncovered at the
top. They consist of a frame of wood,
composed of upright posts, two and a half
feet from each other, ranging on each side,
and strengthened by bars across ; the whole
is supported on stone buttresses, about
three feet from the ground, under which
are the troughs for the salt water to fall
into. The frame is filled with double rows
of faggots of black thorn, ranged from one
end to the other, up to the top, ; they are
placed loosely, so as to admit the air, and
supported firmly in their position by transverse
pieces of wood. In the middle of each
Maison d’Epines is a stone building, containing
the hydraulic machine for pumping
the water to the top of the building ; it is
moved by a water-wheel. When the water
is raised to the top, it is received in channels
on each side, which extend the whole
&l
n
y \
ilP\ - III
* A'l