Marcia 22, 1873.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
7 4/ 
verbal description. We will simply note the fact that 
the metalliferous rocks are surrounded on the north-east 
by black and occasionally graphitic clay-slate, in an 
elliptical manner, and this part of the formation has been 
proved to be the richest in cinnabar, not only in the 
upper but in the lower beds. Where the slate dies away, 
the porphyry widens out, and the cinnabar becomes less 
concentrated, and this renders the explorations more 
uncertain and more costly. The cinnabar occurs dis¬ 
seminated, both in the porphyry and the metamor¬ 
phosed rocks, sometimes in the form of lumps or grains, 
sometimes in veins and little strings, but invariably in an 
altogether irregular manner. The masses occur in the 
form of “shoots,” varying very much in dimensions and 
orientation. 
The porphyry and slaty metamorphic rocks contain, 
besides cinnabar and a little native mercury, iron pyrites, 
gypsum, calcspar, mica, and chlorite. 
As the work consists in discovering and excavating the 
masses of cinnabar, Vallalta mine may be said to be in a 
state of continual exploration. 
About a century ago traces of cinnabar, disseminated 
through the porphyry in a valley on the right bank of 
the torrent Pezzea, induced two Venetian noblemen, Nani 
and Pisani, to commence work there. Two old levels, 
known by their names, still testify to the work they did. 
It seems, however, that soon after beginning to work they 
were obliged to stop, on account of a great error—viz., 
that of going to the expense of carrying the ore to the 
island of Murano, near Venice, where it is said to have 
been distilled. At the commencement of this century, 
Melchior Zanchi, a Venetian of great natural talent and 
a clever miner, set to work alone to reach the centre of 
the metalliferous zone of Vallalta ; his plan was a very 
bold one, and was carried out eventually in 1867. Zanchi 
did not go on very far with his undertaking, as he was 
obliged to stop for want of means. 
Later on, some persons named Schena, Fusina, and 
Nogarola, of Agordo, and Bosio of Primiero, took up the 
works abandoned by Nani and Pisani, ancl made some 
rude attempts to smelt the ore on the spot. 
In the year 1852 the mineral rights of Vallalta belonged 
to three partners—Fusina, Levi, and Bosio. It was then 
that the Venetian Mining Company obtained the permis¬ 
sion to search for ore wherever it liked. This company 
adopted the project of the Government engineer, Joseph 
Bauer, who afterwards became managing director, and, 
with the O’Conor adit, began that series of works which 
were destined to render Vallalta one of the most interest¬ 
ing of mining establishments. The O’Conor adit, after 
having been driven 196 metres, cut the first vein in 1854, 
the ore being quite sparking with native mercury con¬ 
densed at the contact with the slate. 
Encouraged by this success, the company bought up 
all the rights of the above-mentioned proprietors, and 
continued its explorations, not only with the O’Conor adit, 
but also above and below it. The year 1855 saw a large 
metallurgical establishment spring up rapidly and almost 
by magic in the unknown and hitherto solitary Vallalta, 
with two double cupola furnaces, a double reverberatory 
furnace, the necessary condensing apparatuses, buildings 
and houses for sundry purposes, bridges and roads. These 
furnaces failed, however, and it was not until 1857, with 
new furnaces, that the actual production of mercury may 
be said to have begun. Since then the production has 
gone on pretty regularly, although the mine suffered 
great damage from an inundation in 1860, and the works 
were partly washed away in 1868. In the following year, 
Cavaliere G. A. de Manzoni, the actual lessee, took mine 
and works off the company’s hands, and continues to carry 
them on at the present time on his own account. 
The mercuriferous rock has now been worked to a 
vertical depth of 122 fathoms. It is reached by various 
adit levels, and the workings are arranged in thirteen 
horizontal floors. The deepest workings are fifty-four 
fathoms below the lowest adit. The mode of proceeding 
is as follows : As soon as the existence of a mass which 
will pay for working has been proved, a winze is sunk 
through it, and then it is worked away entirely by 
successive horizontal floors. The timber employed is 
generally larch. As fast as the ore is worked away, the 
vacant space is filled up with unproductive rock, some¬ 
times quarried on purpose, to prevent the chambers from 
falling in. 
The ventilation is effected by means of a blast pro¬ 
duced by a great fall of water and carried by wooden 
pipes to the workings. 
The ore arriving from the mine is picked, and unpro¬ 
ductive rock thi'own aavay ; the fine stuff or “ smalls ” is 
moistened with acidulated wat( r, which runs away from 
the condensers, and, made up into compact lumps of nine 
pounds each, can then be treated in the cupola furnaces. 
The cupola furnaces in use at Vallalta are cylindrical, 
lined with fire-brick, and 3 feet 11 inches in diameter lay 
21 feet high. They are built in pairs. Near the base is 
an iron grating, on which the ore rests, and the ore is 
charged from the top by a hopper. The cover of the 
hopper has a water-joint, so the top of the kiln is closed 
hermetically. Before putting in a charge two men work 
away with bars of iron through the grating, and draw 
out some of the burnt ore. The charge is composed of 
ore in large and small pieces, lumps of agglomerated fine 
stuff, and charcoal in the proportion of two per cent, by 
weight. Under the action of heat, in the presence of a 
good draught of air, the cinnabar is decomposed, and the 
mercury liberated passes off as vapour with the products 
of combustion into two chambers near the furnace, and 
thence into two rows of pipes, 3 feet 3 inches in diameter, 
and 49 feet long, in the open air and continually exposed 
to an artificial rain. The major part of the mercury is 
condensed in these tubes, and the residual vapours pass 
through four chambers at the end of the apparatus, and 
then by a third tube to the chimney. In former days 
there were occasionally difficulties with the mercurial 
vapour, which on a sudden change in the temperature 
would sometimes escape from the lower part of the 
furnace, and occasion thereby not only a notable loss of 
mercury, bait also serious injury to the health of the 
workmen, who could not always be cured by the internal 
use of chlorate of potash. Besides, the sulphurous acid 
which escaped from the chimney exercised a very perni¬ 
cious effect upon the surrounding vegetation. 
These evils have been entirely cured by means of a 
most simple exhausting apparatus. To the top of the 
chimney is fixed a descending wooden pipe, which joins 
an almost horizontal pipe, and to the lower end of this is 
attached another vertical pipe, which leads into a subter¬ 
ranean drain. A column of water is brought into the 
side of the last pipe near the top, and, falling through 
some 16 feet, draws with it the gases from the chimney. 
In this manner the chimney always draws properly, and 
the amount of draught can be regulated at pleasure by 
altering the quantity of water. A double cupola furnace 
can treat as much as 150 tons of ore in 24 hours ; and as 
the use of wood for the condensers allows the mercury 
to be drawn off at pleasure, the furnace may remain 
alight for two years or more, in fact, until it requires 
repairs. 
All the mercury is not obtained with its usual bright 
lustre ; the tubes and chambers contain a sooty deposit, 
from which some mercury may be extracted by mechanical 
means on inclined planes, whilst the residue is made up 
into lumps and returned to the furnaces. 
As at Idria, it has been found most convenient to send 
away the mercury in sheepskins. 
The perfection of the metallurgical process at Vallalta 
is proved by the low produce required for profitable 
working. Up to 1870 the average contents of the ore 
did not exceed half a per cent, of mercury ; the loss of 
metal is less than 8 per cent. The mine and works 
employ about two hundred men, the majority being 
miners. The miners work eight-hour shifts, and get 
