851 
THE CHESHIRE SALT-SPRINGS. 
The salt at the British Salt-works, lately visited by the Liverpool Polytechnic 
Society, occurs in two beds, situated one above the other, separated by about 30 ft. of 
clay, intersected by small veins of salt, the two beds together being about 60 ft. thick 
and 300 yards broad, and 1^ mile long. Some rock-salt requires no preparation to con¬ 
vert it into white culinary salt. More frequently, however, it is coloured red or brown 
from the admixture of clay or bitumen ; it then requires to be purified by solution and 
recrystallization. 
The brine-springs of Cheshire do not rise to the surface of the ground. They emerge 
from the surface of the rock, and when the spring is tapped will rise in the bore-hole 
from 80 to 90 ft. The shaft is 6 ft. square, and about 180 ft. deep. The sides of the 
shafts are carefully boarded with planks, and an inner planking of 6-in. boards, 4 ft. 
square, is then built in, and the space between the boards well puddled with clay to 
keep out fresh-water surface springs. An iron pipe, about 9 in. internal diameter, is then 
let down into the boring. The brine will rise in this pipe about 90 ft.; it has consequently 
to be lifted by a pump to about the same extent. A continuation of the pipe from the 
pump conducts the brine into a larger reservoir. The reservoir, which may be about 
200 ft. long by about 60 or 80 ft. broad, and 4 to 7 ft. deep, is not built for the purpose 
of allowing sedimentary matter to deposit, for the brine as it is pumped up is perfectly 
clear and free from particles in suspension. It is of a clear sea-green colour, and the 
reservoirs are built to serve merely as a store of brine on a high level, and from which 
it may be drawn down to supply evaporating pans as needed. 
The evaporating pans are contained in a shed, open at the sides to permit free cur¬ 
rents of air to pass over their surface. The pans are set in a firm foundation of bricx- 
work, which, however, does not extend up the sides. There ai;e generally four furnaces 
to each pan, and the flues, so built as to support the pan, radiate over the whole bottom. 
The Cheshire brines, which have a specific gravity of 1'2, and contain about 24 per 
cent, of common salt, are of so pure a quality that they require no preliminary februa- 
tion. The brine, therefore, is at once run into the evaporating pans. The pans are of 
i-in. iron boiler-plates, riveted together. They incline somew'hat towards the end 
furthest from the fires. The inclination is from 6 to 8 in. in the whole length. 
Three kinds of salt are manufactured. The difference consists in the size of the 
crystal, depending upon the rapidity with which the evaporation is conducted; thus the 
finest grained salt is made by rapid boiling, the coarsest at about a temperature of 150 
and the medium quality between these two points. _ 
One system of the evaporating process is as follows:—Brine is run into a pan until it 
is three parts full. A little ox-blood or white of egg, or any albuminous matter, is then 
thrown in to assist in the formation of a scum. The brine is then brought to the boil 
as rapidly as possible, and a scum which forms on the top is removed by lightly skim¬ 
ming the surface with a piece of board. The crystals of salt begin to separate almost 
as soon as the brine is brought to the seethiug-point, and when about half of the w r ater 
has been evaporated fresh brine is run in. The salt that has boiled out is removed twice 
in twenty-four hours. This operation is effected by a perforated scoop, and the salt is 
put into wooden moulds, or tubs, about 18 in. high, and 9 in. broad at the top, diminish¬ 
ing to about 7 in. at the bottom. These tubs are put into the salt-pan to be filled, and 
stand on a ledge on the side about 6 in. from the bottom of the pan. W hen the tubs 
are full the salt is slightly pressed down, and the tubs are removed from the ledge to a 
perforated floor, so that the mother liquid may be drained away from the salt. Vv en 
the salt in the tub has drained twelve hours the tubs are reversed, and then withdrawn 
from the squares of salt, which are removed to the drying chamber, where they are 
allowed to remain until they become dry. The pans are not allowed to cool, except for 
the purpose of cleansing, the brine being repeatedly pumped in, the process of evapora¬ 
tion being continuous. The operation called “ dodging, ’ or “ scabbing, is performed 
with a pickaxe furnished with a long handle, and having the iron flukes flattened at 
the ends. A man stands on the floor that runs around the pan, and by striking wit 
the axe he loosens the incrustation, and then removes it with a rake and spade, lhe 
scab consists of a little clay and sulphate of lime, but principally of common salt winch 
has been burnt on the bottom of the pan .—Mining Journal. 
