Sulphur, or brimstone, is a hard, brittle substance of various colors,
from brilliant yellow to dark brown, without smell when cool, of a
mild taste, and burns with a pale blue flame, emitting pungent and
suffocating fumes. Its specific gravity is from 1.9 to 2.1.
Sulphur exists more or less in all known countries, but the island of
Sicily, it is thought, is the only place where it is produced on a
large scale, and consequently that island appears to command the
market. Small quantities have been found in the north of Italy, the
Grecian Archipelago, Russia, Austria, Poland, France, Spain, eastern
shores of Egypt, Tunis, Iceland, Brazil, Central America, and the
United States. Large quantities are said to exist in various countries
of Asia, but it is understood to be impracticable to utilize the same,
consequent upon the distance from any commercial port and the absence
of rail or other roads.
Sulphur is of two kinds, one of which is of volcanic emanation, the
other being closely allied to sedimentary rocks. The latter is found
in Sicily, on the southern and central portions of the island. Mount
Etna, situated in the east, seems to exert no influence in the
formation of brimstone. There are various hypotheses relative to its
natural formation. Dr. Philip Swarzenburg attributes it to the
emanations of sulphur vapor expelled from metallic matter existing in
the earth, consequent upon the fire in the latter, while Professors
Hoffman and Bischoff ascribe it to the decomposition of sulphureted
hydrogen. Hoffman believes the sulphureted hydrogen must have passed
through the fissures of stratified rocks, but Bischoff is of opinion
that the sulphureted hydrogen must have been the result of the
decomposition of sulphate of lime in the presence of organic matter.
The theory of others is that sulphur owes its origin to the
combination of lacustrine deposits with vegetable matter, and others
again suppose that it is due to the action of the sea upon animal
remains. The huge banks of rock salt often met with in the vicinity of
sulphur mines, and which in some places stretch for a distance of
several miles, seem to indicate that the sea has worked its way into
the subsoil. Fish and insects, which are frequently found in strata of
tripoli, which lie under sulphur beds, induce the belief that lakes
formerly existed in Sicily.
The following is a list of the various strata which form part of the
crust of the earth in Sicily, according to Professor Mottura, an
Italian geologist:
_Pliocene._--Sandstone; coarse calcareous rock; marl.
_Upper Miocene._--Calcareous marl; gypsum, etc.; sulphur embedded in
calcareous limestone; silicious limestone; tripoli, containing fossils
of fish, insects' eggs, etc.
_Middle Miocene._--Sandstone containing quartz, intercalated with marl
of a saltish taste.
_Lower Miocene._--Rock salt; blue marl, containing petroleum and
bitumen; flintstone; ferruginous clay, mixed with aragonite and
bituminous schists; ferruginous and silicious sandstone.
_Eocene._--Limestone, containing diaspores and shells.
At times one or another of the strata disappears, while the order of
some is slightly reversed on account of the broken state of the crust.
Upon the whole, however, the above has been generally observed in the
various mines by the author referred to.
Sulphur mines have been operated in Sicily over three hundred years,
but until the year 1820 its exportation was confined to narrow limits.
At present the number of mines existing in Sicily is about three
hundred, nearly two hundred of which, being operated on credit, are,
it is understood, destined to an early demise. It is said that there
are about 30,000,000 tons of sulphur in Sicily at present, and that
the annual production amounts to about 400,000 tons. If this should be
true, taking the foregoing as a basis, the supply will become
exhausted in about seventy-five years.
In 1819 a law was passed in Italy, which is still in force, governing
mining in Sicily, which provides that should a land owner discover ore
in his property he would be the owner thereof, and should have the
right to mine, operate, or rent the property to others for that
purpose, but if he should decline to operate his mines or to rent them
to others to be operated, the state would rent them on its own
account.
Royalties vary from 12 to 45 per cent. They are paid according to the
quality of the ore and the facilities for producing sulphur; 25 per
cent. may, however, be taken as an average. There is a land tax of 36
per cent. of the net income, which is usually paid by the owners and
lessees of the mines, in proportion to the quantity of sulphur which
they produce. The export duty is 10 lire per ton. All mines are
inspected by government officials once a year, and the owners are
required to furnish the state with plans of the works and their
progress, with a view to insure the safety of the workmen and to
ascertain the extent of the property.
Those who rent their mines receive from 10 to 40 per cent. of the
sulphur produced. Leases are valid for such period as the contracting
parties may stipulate therein. The general limit, however, is nine
years. The average lease is 25 per cent., 40 per cent. being paid only
when the mines are very favorably situated and the production good.
Some lessees prefer paying a considerable sum in cash in advance, at
the beginning of the term of the lease, and giving 15 or 20 per cent.
in sulphur annually thereafter, instead of a higher percentage.
The external indications of the presence of sulphur are the appearance
of gypsum and sulphurous springs. These are indubitable signs of the
presence of sulphur, and when discovered the process resorted to here,
in order to reach the sulphur, is to bore a hole sufficiently large to
admit a man, after which steps are constructed in the passage in order
to facilitate the workmen in going to and fro. These steps extend
across the passage, and are about 25 centimeters high and 35 broad.
The inclination of the holes or passages varies from 30 to 50 degrees.
Upon attaining the depth of several meters water is often met with,
and in such considerable quantity that it is impossible to proceed.
Hence it becomes necessary to either pump the water out or retreat in
order to bore elsewhere. It is often necessary to bore several
passages in order to discover the ore or seam of sulphur. When,
however, it has been discovered the passages are made to follow its
direction, whether upward or downward. As the direction of seams is in
most cases irregular, that of the passages or galleries is likewise.
Where the ore is rich and the matrix yielding, the miners break it by
means of pick-axes and pikes, but when such is not the case gunpowder
is resorted to, the ore in this case being carried to the surface by
boys. The miners detach the ore from the surrounding material, and the
cavities which ensue in consequence assume the appearance of vast
caves, which are here and there supported by pillars of rock and ore
in order to keep them from falling or giving way. In order to
strengthen the galleries sterile rock is piled upon each side and
cemented with gypsum. In extensive mines, however, these supports and
linings are too weak, and not infrequently, as a result, the galleries
and caverns give way, occasionally causing considerable havoc among
the miners. Sulphur is found from the surface to a depth of 150
meters. The difficulties met with in operating mines are numerous, and
among the greatest in this category are water, land slides,
irregularity of seam, deleterious gases, hardness of rocks and
matrices. Of these difficulties, water is the most frequently met
with. Indeed, it is always present, and renders the constant use of
pumps necessary. At one time miners were allowed to dig where they
pleased so long as sulphur was extracted, the consequence being that
in groups of mines, the extent and direction of which being unknown to
their respective owners, one mine often fell into or upon another,
thus causing destruction to life and property. It was largely for this
reason, it is understood, that the government determined to require
owners and lessees of mines to furnish plans thereof to proper
authority, and directed that official inspection of the mines should
be made at stated periods. In order to comply with the decree of the
government it became necessary to employ mining engineers to draw the
plans, etc., and those employed were generally foreigners. In the
system of excavation described no steam power is employed. Pumping is
performed by means of primitive wooden hand pumps, and when sufficient
ore has been collected it is conveyed on the backs of boys to the
surface--a slow, costly, and difficult procedure. This system may,
however, be suitable to small mines, but in large mines there is no
economy in hand labor; indeed, much is lost in time and expense by it.
For this reason steam has been introduced into the larger and more
important mines. The machinery employed is a hoisting apparatus, with
a drum, around which a coil is wound, with the object of hoisting and
lowering trucks in vertical shafts. Steam pumps serve to extract the
water. The force of the hoisting apparatus varies from 15 to 50 horse
power. The fuel consumed is English and French coal, the former being
preferred, as it engenders greater heat. The cost of a ton of coal at
the wharf is $4.40, whereas in the interior of the island it costs
about $10. The shafts or pits are made in the ordinary way, great care
being taken in lining them with masonry in order to guard against land
slides. In level portions of the country vertical shafts are
preferred, but where the mine is situated upon a hill a debouch may
often be found below the sulphur seam, when an inclined plane is
preferred, the ore being placed in trucks and allowed to run down the
plane on rails until it reaches the exterior of the mine, where it
suddenly and violently stops, and as a result the trucks are emptied
of their load, when they are drawn up the plane to be refilled; and
thus the process goes on indefinitely. In these mines a gutter is made
in the inclined plane which carries off the water, thus dispensing
with the necessity of a pump and the requisites to operate it. The
galleries and inclined shafts are lined with beams of pine or larch,
which are brought hither from Sardinia, as Sicily possesses very
little timber. The mines are illuminated by means of iron oil lamps,
the wicks of which are exposed. The lamps are imported from Germany.
In certain cases an earthenware lamp, made on the island, and said to
be a facsimile of those used by the Phoenicians, is employed. This
lamp is made in the shape of a small bowl. It is filled with oil and a
wick inserted, which hangs or extends outward, and is thus ignited,
the flame being exposed to the air. Safety lamps are unknown, and
those described are generally secure. Few explosions take place--only
when confined carbonic hydrogen is met with in considerable
quantities, and when the ventilation is not good. In this case the
mine is easily ignited, and once on fire may burn for years. The only
practical expedient for extinguishing the fire is to close all inlets
and outlets in order to shut off the air. This, however, is difficult
and takes time. Notwithstanding the closing of communications, the
gases escape through the fissures and openings which obtain
everywhere, and the ingress of air makes it next to impossible to
extinguish the fire; hence it burns indefinitely or until the mine is
exhausted. Occasionally the burning of a mine results beneficially to
its owners, in that it dispenses with the necessity of smelting, and
produces natural, refined sulphur.
Galleries in extent are usually 1.20 by 1.80 meters, and when ore is
not found and it becomes necessary to extend the galleries, laborers
are paid in accordance with the progress they may make and the
character of the rock, earth, etc., through which it may be necessary
to cut, as follows:
Silicious limestone, 60 lire per meter; daily progress, 0.20 meter.
Gypsum, 50 lire per meter; daily progress, 0.30 meter.
Marl, 30 lire per meter; daily progress, 0.50 meter.
Clay, 15 lire per meter; daily progress, 1 meter.
Laborers working in the ore are paid 4.30 lire per ton. This includes
digging, extracting, and illumination. In some mines, however, the
laborers are paid when the sulphur is fused and ready for exportation.
One ton of sulphur, or its equivalent (say from 40 to 50 lire), is the
amount generally paid. In mines where this system obtains the
administration is only responsible for their maintenance. Each miner
produces on an average about 1½ tons of ore daily, and when the works
are not more than 40 meters in depth he employs one boy to assist him,
two boys when they reach 60 meters, and three when under 100 meters.
These boys are from seven to sixteen years of age, and are paid from
0.85 to 1.50 lire per day by the miner who employs them. They carry
from 1,000 to 1,500 pounds of ore daily, or in from six to eight
hours. The food consumed by miners is very meager, and consists of
bread, oil, wine, or water; occasionally cheese, macaroni, and
vegetables are added to the above.
Mining laborers generally can neither read nor write, and when
employed in mines distant from habitations or towns, live and sleep
therein, or in the open air, depending on the season or the weather.
In a few mines the laborers are, however, provided with suitable
dwelling places, and a relief fund is in existence for the succor of
the families of those who die in the service. This fund is greatly
opposed by the miners, from whose wages from 1 to 2 per cent. is
deducted for its maintenance. In the absence of a fund of this
character, the sick or infirm are abandoned by their companions and
left to die. Generally miners are inoffensive when fairly dealt with.
They are said to be indolent and dishonest as a rule. The managers of
mines receive from 3,000 to 5,000 lire per annum; chief miners from
1,500 to 2,500 lire; surveyors, 700 to 1,000 lire; and weighers and
clerks, from 1,000 to 2,000 lire per annum. The total number of mining
laborers in Sicily is estimated at about 25,000.
The ore for fusion of the first grade as to yield contains from 20 to
25 per cent. of sulphur, that of the second grade from 15 to 20 per
cent., and of the third grade 10 to 15 per cent. The usual means
adopted for extracting sulphur from the ore is heat, which attains the
height of 400 degrees Centigrade, smelting with the kiln, which in
Sicilian dialect is called a "calcarone." The "calcarone" is capable
of smelting several thousand tons of ore at a time and is operated in
the open air. Part of the sulphur is burned in the process of smelting
in order to liquefy the remainder. "Calcaroni" are situated as closely
to the mouth of a shaft as possible, and if practicable on the side of
a hill, in order that when the process of smelting is complete, the
sulphur may run down the hill in channels prepared for the purpose.
The shop of a "calcarone" is circular and the floor has an inclination
of from 10 to 15 degrees. A design of a "calcarone" is herewith
inclosed. The circular wall is made of rude stone work, cemented
together with gypsum. The thickness of the wall at the back is 0.50
meter, and from this it gradually becomes thicker until in front,
where it is 1 meter, when the diameter is to be 10 meters. In front of
the thickest part of the wall an opening is left, measuring 1.20
meters high and 0.25 meter broad.
Through this opening the liquid sulphur flows. Upon each side of this
opening two walls are built at right angles with the circular wall, in
order to strengthen the front of the kiln. These walls are 80
centimeters thick each and are roofed. A door is hinged to these
walls, thus forming a small room in front of each kiln in which the
keeper thereof resides from the commencement to the termination of the
flow of sulphur. The inclined floor of the kiln is made of stone work
and is covered with "ginesi," the name given to the refuse of a former
process of smelting. The stone work is 20 centimeters thick, and the
"ginesi" covering 25 centimeters, which gradually becomes thicker as
it approaches its lowest extremity. The front part of the circular
wall is 3.50 meters high and the back 1.80 meters. The interior of the
wall is plastered with gypsum in order to render it impermeable.
The cost of a "calcarone" of about 500 tons capacity is 800 lire. The
capacity varies from 40 to 5,000 tons, or more, depending upon
circumstances. If a mine is enabled to smelt the whole year round, the
smaller "calcaroni," being more easily managed, are preferred; the
inverse is the case as to the larger "calcaroni," when this is
impracticable. When a "calcarone" is situated within 100 meters of a
cereal farm, its operation is prohibited by law during the summer,
lest the fumes of the sulphur should destroy the crop.
When, however, the distance is greater from the farm or farms than 100
meters, smelting is permitted; but should any damage ensue to the
crops as a result of the fumes, the owners of the "calcaroni" are
required to liquidate it. Therefore the mines which are favorably
situated smelt the entire year, and employ "calcaroni" of from 40 to
500 tons, as there is less risk of a process failing, which
occasionally happens, and for the reason that the ore can be smelted
as soon as it is extracted; whereas, when kilns or "calcaroni" are
situated within or adjacent to the limit adverted to, they can only be
operated five or six months in the year, consequent upon which the ore
is necessarily stacked up all through the summer or until such time as
smelting may be commenced without endangering the crops, when it
becomes necessary to use "calcaroni" whose capacity amounts to several
thousand tons. As intimated, these large "calcaroni" are not so
manageable as those of smaller dimensions, and as a result many
thousands of tons of sulphur are lost in the process of smelting,
besides perhaps the loss of an entire year in labor. Again, the ore
deteriorates or depreciates when long exposed to the air and rain, all
of which, when practicable, render the kilns or "calcaroni" of the
smaller capacity more advantageous and lucrative to those operating
sulphur mines in Sicily. Smelting with a "calcarone" of 200 tons
capacity consumes thirty days, one of 800 tons 60 days, and with a
"calcarone" of 2,000 tons capacity from 90 to 120 days are consumed.
In loading or filling the "calcaroni," the larger blocks of ore are
placed at the bottom as well as against the mouth, in order to keep
the lower part of the kiln as cool as possible with a view of
preventing the liquid sulphur from becoming ignited as it passes down
to where it makes its exit, etc. The blocks of ore thus first placed
in position are, for obvious reasons, the most sterile. After the
foundation is thoroughly laid the building of the "pile" is proceeded
with, the larger blocks being placed in the center to form, as it
were, the backbone of the pile; the smaller blocks of ore are arranged
on the outside of these and in the interstices. The shape or form of
the pile when completed is similar to a truncated cone, and when
burning the kiln looks like a small volcano. When the kiln has been
filled with ore, the whole is covered with ginesi with a view of
preventing the escape of the fumes. The ore is then ignited by means
of bundles of straw, impregnated or saturated with sulphur, being held
above the thin portion of the top of the kiln, which is at once closed
with ginesi, and the "calcarone" is left to itself for about a week.
During the burning process the flames gradually descend, and the
sulphur contained in the ore is melted by the heat from above. In
about seven or eight days sulphuric fumes and sublimed sulphur
commence to escape, when it becomes necessary to add a new coat of
ginesi to the covering and thus prevent the destruction of vegetation
by the sulphur fumes. The mouth of the kiln, which has been left open
in order to create a draught, is closed up about this time with gypsum
plaster. When the sulphur is all liquefied it finds its way to the
most depressed part of the kiln, and there, upon encountering the
large sterile blocks, quite cold, already referred to, solidifies. It
is again liquefied by means of burning straw, whereupon an iron trough
is inserted into a mouth made in the kiln for the purpose, and the
reliquefied sulphur runs into it, from which it is immediately
collected into wooden moulds, called "gadite," and which have been
kept cool by being submerged in water. Upon its becoming thoroughly
cool the sulphur is taken out of the moulds referred to, and is now in
solid blocks, each weighing about 100 weight. Two of these blocks
constitute a load for a mule, and cost from 4 to 5 francs.
The above is the result when the operation succeeds; but this is not
always the case. At times the sulphur becomes solidified before it
reaches the mouth of the kiln, because of the heat not being
sufficient to keep it liquid in its passage thereto, and other
misfortunes not within control, and consequent upon the use of the
larger kilns, or "calcaroni."
When the sulphur ceases to run from the kiln, the process is complete.
The residue is left to cool, which consumes from one to two months.
The cooling process could be accomplished in much less time by
permitting the air to enter the kiln, but this would be destructive to
vegetation, and even to life, consequent upon the fumes of the
sulphur. The greatest heat at a given time in a kiln is calculated to
be above 650 degrees Centigrade--that is, at the close of the process.
This enormous heat is generally allowed to waste, whereas it is
understood it could be utilized in many ways. A gentleman of the name
of Gill is understood to have invented a recuperative kiln, which
will, if generally adopted, utilize the heat of former processes
named. A ton of ore containing about 25 per cent. of sulphur yields
300 pounds of sulphur. This is considered a good yield. When it yields
200 pounds it is considered medium, and poor when only 75 pounds.
Laborers are paid 0.40 lire per ton for loading and unloading kilns,
and from thirty to forty hands are employed at a time. The keeper of a
kiln receives from 2 to 2.50 lire per day.
Notwithstanding the "calcarone" has many defects, it is the simplest
and cheapest mode of smelting, and is preferred here to any other
system requiring machinery and skilled labor to operate it.
The following are the principal furnaces in use here: Durand's;
Hirzel; Gill and Kayser's system of fusion; Conby Bollman process;
Thomas steam process of smelting; and Robert Gill's recuperative
kilns.
There are seven qualities or grades of sulphur, viz.: