The portion of mercury not condensed in the range of aludels, fg, which is the most considerable, goes in the state of vapour, into a chamber k; but in passing under a partition, a certain portion is deposited in a cistern i, filled with water. The greater part of the vapours diffused in the chamber k' is thereby condensed, and the mercury

1174

falls down upon the two inclined planes which form its bottom. What may still exist as vapour passes into an upper chamber k' by a small chimney n. On one of the sides of this chamber there is a shutter which may be opened at pleasure from below upwards, and beneath this shutter, there is a gutter into which a notable quantity of mercury collects. Much of it is also found condensed in the aludels. These facts prove that this process has inconveniences, which have been tried to be remedied by the more extensive but rather unchemical grand apparatus of Idria.

Details of the aludel apparatus.—25 are set in each of the 12 ranges, seen in figs. 1173, 1174, constituting 300 pear-shaped stoneware vessels, open at both ends, being merely thrust into one another, and luted with loam. a, is the door of the fire-place; c, the perforated arches upon which the ore is piled in the chamber e, through the door d, and an orifice at top; the latter being closed during the distillation; ƒƒ are vents for conducting the mercurial vapours into two chambers i, separated by a triangular body of masonry mn; h is the smoke chimney of the fire-place; o o are the ranges of aludels, in connection with the chamber i, which are laid slantingly towards the gutter q, upon the double inclined plane terrace, and terminate in the chamber hq; this being surmounted by two chimneys t. The mercury is collected in these aludels and in the basins at 9 and p, fig. 1173. r is a thin stone partition set up between the two principal walls of each of the furnaces. is the stair of the aludel terrace, leading to the platform which surmounts the furnace; z is a gutter for conducting away the rains which may fall upon the buildings, fig. 1174.

3. Great apparatus of Idria.—Before entering into details of this laboratory, it will not be useless to state the metallurgic classification of the ores treated in it. 1. The ores in large blocks, fragments, or shivers, whose size varies from a cubic foot to that of a nut. 2. The smaller ores, from the size of a nut to that of grains of dust. The first class of large ores comprises three subdivisions, namely; a, blocks of metalliferous rocks, which is the most abundant and the poorest species of ore, affording only one per cent. of mercury; b, the massive sulphide of mercury, the richest and rarest ore, yielding 80 per cent. when it is picked; c, the fragments or splinters proceeding from the breaking and sorting, and which vary in value, from 1 to 40 per cent.

The second class of small ores comprises: d, the fragments or shivers extracted from the mine in the state of little pieces, affording from 10 to 12 per cent. ; e, the kernels of ore, separated on the sieve, yielding 32 per cent.; f, the sands and paste called schlich,

1175

Hn

K

obtained in the treatment of the poorest ores, by means of the stamps and washing tables; 100 parts of this schlich give at least 8 of quicksilver.

The general aspect of the apparatus is indicated by figs. 1175, 1176, and 1177. Fig. 1177 represents the exterior, but only one half, which is enough, as it resembles exactly the other, which is not shown. In these three figures the following objects may be distinguished; figs. 1175, 1176, a, door of the fire-place; b, the furnace in which beechwood is burned mixed with a little fir-wood; c, door of the ash-pit, extended beneath; d, a space in which the ores are deposited upon the seven arches, I to 7, as indicated in figs. 1175 and 1178; e e, brick tunnels, by which the smoke of the fuel and the vapours of mercury pass, on the one side, into successive chambers fk.

fabij klare passages which permit the circulation of the vapours from the furnace

a bed, to the chimneys ll. Figs. 1175 and 1176 exhibit clearly the distribution of these openings on each side of the same furnace, and in each half of the apparatus, which is

double, as fig. 1176 shows; the spaces without letters being in every respect similar to the spaces mentioned below. Fig. 1176 is double the scale of fig. 1175.

1177

m m', fig. 1176, are basins of reception, distributed before the doors of each of the chambers fkfk. The condensed mercury which flows out of the chambers is conveyed thither. n n' is a trench into which the mercury, after being lifted into the basins m, is poured, so that it may run towards a common chamber o, in the sloping direction indicated by the arrows. o leads to the chamber where the mercury is received into a porphyry trough; out of which

it is laded and packed up in portions of 50 or 100 lbs. in sheep-skins prepared with alum. pp, fig. 1175, are vaulted arches, through which a circulation may go on round the furnace a bed, on the ground level. qq are the vaults

of the upper stories. rr, fig. 1177, vaults which permit access to the tunnels e' e'', fig. 1178.

8s and tt, fig. 1177, are the doors of the chambers f k and fk. These openings are shut during the distillation by wooden doors faced with iron, and luted with a mortar of clay and lime. uu is the door of the vaults 1 to 7 of the furnace represented in fig. 1175. These openings are hermetically shut, like the preceding. vv, fig. 1175, are superior openings of the chambers, closed during the operation by luted plugs; they are opened afterwards to facilitate the cooling of the apparatus, and to collect the mercurial soot. xyz, fig. 1178, are floors which correspond to the doors u u', of the vaults 1 to 7, fig. 1177. These floors are reached by stairs set up in the different parts of the building which contains the whole apparatus.

y

a

b

1178

On the lower arches the largest blocks of metalliferous rock are laid; over these the less bulky fragments are arranged, which are covered with the shivers and pieces of less dimension. On the middle vaults, the small ore is placed, distributed into cylindrical pipkins of earthenware, of 10 inches diameter and 5 inches depth. The upper vaults receive likewise pipkins filled with the sands and pastes called schlich.

In 3 hours, by the labour of 40 men, the two double sets of apparatus are charged, and all the apertures are closed. A quick fire of beech-wood is then kindled; and when the whole mass has become sufficiently heated, the sulphuret of mercury begins to vaporise; coming into contact with the portion of oxygen which had not been carbonated by combustion, its sulphur burns into sulphurous acid, while the mercury becomes free, passes with the other vapours into the chambers for condensing it, and precipitates in the liquid form at a greater or less distance from the fire-place. The walls of the chambers and the floors, with which their lower portion is covered, are soon coated over with a black mercurial soot, which, being treated anew, furnishes 50 per cent. of mercury. The distillation lasts from 10 to 12 hours; during which time the whole furnace is kept at a cherry-red heat. A complete charge for the two double apparatus consists of from 1000 to 1300 quintals of ore, which produce from 80 to 90 quintals of running mercury. The furnace takes from 5 to 6 days to cool, according to the state of the weather; and if to that period be added the time requisite for withdrawing the residuums, and attending to such repairs as the furnace

may need, it is obvious that only one distillation can be performed in the course of a week.

In the works of Idria, in 1812, 56,686 quintals (of 110 lbs. each) and a half of quicksilver ores were distilled, after undergoing a very careful mechanical preparation. They afforded 4832 quintals of running mercury; a quantity corresponding to about 8 per cent. of the ore. These smelting works are about 180 feet long and 30 feet high.

It has been long well known, that quicksilver may be most readily extracted from cinnabar, by heating it in contact with quicklime. The sulphur of the cinnabar combines, by virtue of a superior affinity with the lime, to the exclusion of the quicksilver, to form sulphides of lime and calcium, both of which being fixed hepars, remain in the retort, while the mercury is volatilised by the heat. In a few places, hammerschlag, or the iron cinder driven off from the blooms by the tilting hammer, has been used instead of lime in the reduction of this mercurial ore, whereby sulphurous acid and sulphide of iron are formed.

The annual production of the Bavarian Rhine provinces has been estimated at from 400 to 550 quintals; that of Almaden, at 22,000 quintals; and that of Idria, at about 1500 quintals.

All the plans hitherto prescribed for distilling the ore along with quicklime are remarkably rude. In that practised at Landsberg near Obermoschel, there is a great waste of labour, in charging the numerous small cucurbits; there is a great waste of fuel in the mode of heating them; a great waste of mercury by the imperfect luting of the retorts to the receivers, as well as the imperfect condensation of the mercurial vapours; and probably a considerable loss by pilfering.

The modes practised at Almaden and Idria are, in the greatest degree barbarous; the ores being heated upon open arches, and the vapours attempted to be condensed by enclosing them within brick or stone and mortar walls, which can never be rendered either sufficiently tight or cool.

To obviate all these inconveniences and sources of loss, the proper chemical arrangements suited to the present improved state of the arts ought to be adopted, by which labour, fuel, and mercury might all be economised to the utmost extent. The only apparatus fit to be employed is a series of cast iron cylinder retorts, somewhat like those employed in the coal gas works, but with peculiarities suited to the condensation of the mercurial vapours. Into each of these retorts, supposed to be at least one foot square in area, and 7 feet long, 6 or 7 cwt. of a mixture of the ground ore with the quicklime, may be easily introduced, from a measured heap, by means of a shovel. The specific gravity of the cinnabar being more than 6 times that of water, a cubic foot of it will weigh more than 34 cwt.; but supposing the mixture of it with quicklime (when the ore does not contain the calcareous matter itself) to be only thrice the density of water, then four cubic feet might be put into each of the above retorts, and still leave 1 cubic feet of empty space for the expansion of volume which may take place in the decomposition. The ore should certainly be ground to a moderately fine powder, by stamps, iron cylinders, or an edge wheel, so that when mixed with quicklime, the cinnabar may be brought into intimate contact with its decomposer, otherwise much of it will be dissipated unproductively in fumes, for it is extremely volatile.

1179

K

I

Figs. 1179, 1180, 1181 represent a cheap and powerful apparatus contrived by Dr. Ure at the request of the German Mines Company of London, and which was mounted at Landsberg, near Obermoschel, in the Bavarian Rhein-Kreis.

Fig. 1179 is a section parallel to the front elevation of three arched benches of retorts, of the size above specified. Each bench contains 3 retorts, of the form represented by a a a. 1, is the single fire-place or furnace, capable of giving adequate ignition by coal or wood, to the three retorts. The retorts were built up in an excellent manner, by an English mason perfectly acquainted with the best modes of erecting coal-gas retorts, who was sent over on purpose.

The

In the section, fig. 1180, a is the body of the retort; its mouth at the right hand end is shut, as usual, by a luted iron lid, secured with a cross-bar and screw bolts; its other end is prolonged by a sloping pipe of cast iron, 4 inches in diameter, furnished with a nozzle hole at L, closed with a screw plug. Through this hole a wire rammer may be introduced, to ascertain that the tube is pervious, and to cleanse it from the mercurial soot, when thought necessary. c, is a cross section of the main condenser, shown in a longitudinal section at c c, fig. 1181. This pipe is 18 inches in diameter, and about 20 feet long. At a a, &c., the back ends of the retorts are seen, with the slanting tubes bb, &c., descending through orifices in the upper surface of the condenser pipe, and dipping their ends just below the water-line hi. g, is the cap of a water valve, which removes all risk from sudden expansion or condensation. condenser is placed within a rectangular trough, made either of wood or stone, through which a sufficient stream of water passes to keep it perfectly cool, and repress every trace of mercurial vapour, and it is laid with a slight inclination from i to h, so that the condensed quicksilver may spontaneously flow along its bottom, and pass through the vertical tube D into the locked up iron chest, or magazine e. This tube Dis from the beginning closed at bottom, by immersion in a shallow iron cup, always filled with mercury. k is a graduated gauge rod, to indicate the progressive ac cumulation of quicksilver in the chest, without being under the necessity of unlocking it.

This air-tight apparatus was erected some years ago, and was found to act perfectly well. The whole cost of the 9 large retorts, with their condensing apparatus, iron magazine, &c., was very little more

1180

a

than two hundred pounds! As the retorts are kept in a state of nearly uniform ignition, like those of the gas works, neither they nor the furnaces are liable to be injured in their joints by the alternate contractions and expansions, which they would

II

h

C

1181

C

inevitably suffer if allowed to cool; and being always ready heated to the proper pitch for decomposing the mercurial ores, they are capable of working off a charge, under skilful management, in the course of 3 hours. Thus, in 24 hours, with a relay of labourers, 8 charges of at least 5 cwts. of ore each might be smelted 2 tons, with 3 retorts, and 6 tons with 9 retorts; with a daily product from the rich ores of Almaden, or even Idria, of from 12 cwts. to 20 cwts. Instead of 3 benches of 3 retorts each. Dr. Ure recommends 15 benches, containing 45 retorts, to be erected for either the Almaden or Idria mines; which, while they would smelt all their ores, could be got for a sum not much exceeding 1000l., an outlay which they would reitaburse within a month or two.

Dr. Tobin gives an interesting account of the mercurial mines in California, in a letter from which we abstract the following.

"That part of California where I have been residing, and that which I have just visited,

consists of three long ranges of trap mountains, with two wide valleys dividing them, the valley of the San Joaquin, and the valley of Santa Clara. Near this last place are the quicksilver mines of New Almaden, where I have been working. The matrix of the cinnabar ore is the same trap of which the mountain ranges are composed, and as yet only one great deposit of this ore has been found, though traces of quicksilver ores have been discovered in other places. The ores are composed solely of sulphuret of mercury (averaging 36 per cent.), red oxide of iron and silica; and had the mine been properly worked from the commencement almost any quantity of ore might be extracted; it now, however, more resembles a gigantic rabbit warren than a mine. The owners have lately sent out a German miner, an experienced and practical man, who, if he stays here will eventually put the mine into some kind of order. Its greatest depth is about 150 feet, and the weekly extraction of ores varies from 100 to 150 tons. I have now got 16 cylinders at work, producing 1400 to 1500 lbs. daily. The result to me was satisfactory, but not so to the proprietor, on account of the expense of fuel and labour: he accordingly got a blacksmith, who had been sent here to put up the water wheel, to build him a small furnace, without consulting me This man sent a friend of his, not liking to come himself, to look at the plans I had, of the furnaces of Idria and Almaden, and then erected a small and miserable furnace to hold one ton of ore, upon a disimproved plan of those of Idria. With this he obtained from the richest ores (65 to 72 per cent.) 38 per cent. of mercury, of course with the consumption of very little wood and with little labour. The proprietor immediately determined to have six similar furnaces built, and with great regret allowed me to erect one good furnace, and afterwards a second one.

at all.

"Now take the results of the year's work, and you can judge whether the report sent you is true or not, that the blacksmith has superseded me. Before the year was half out, he got tired of attempting to compete with my furnaces, and left in disgust. The cylinders produced 251,616 lbs of mercury.

(but were stopped in November on ac

count of expense of working)

The first furnace, working only from November 1st, to July 1st, 1851, gave

The second furnace, working only from March 18th to July 1st, gave

"The product of the six furnaces, working for a much longer period, as they went into operation long before mine, was only 544,000 lbs. making a total product for the year of about 18,000 quintals.'

Mr. Russell Bartlett, the United States Commissioner on the Mexican and United States Boundary Question, who visited California in 1853, states that the quantity of quicksilver produced annually at New Almaden, exceeds 1,000,000 lbs. During the year 1853 the total exports from San Francisco amounted to 1,350,000 lbs. valued at 683,189 dollars. All this, together with the large amount used in California, was the product of the New Almaden mine in the Santa Clara county, 12 miles from the town of San José, which is 54 miles from the city of San Francisco. The working of the mine was begun in the year 1846-7, by an English company, but for some reasons was not profitable. In 1849-50 it fell into American hands. The following shows to what points the quicksilver was exported in 1853:-Hong Kong, 423,150 lbs.; Shanghae, 60,900 lbs.; Canton, 27,450 lbs.; Whampoa, 22,500 lbs.; Calcutta, 3,750 lbs; Mazatlan, 210,825 lbs.; Mazatlan and San Blas, 19,125 lbs.; San Blas, 145,652 lbs.; Callao, 135,000 lbs. ; Valparaiso, 148,275 lbs.; New York, 138,375 lbs. ; Philadelphia, 75,000 lbs. The ore is cinnabar of a bright vermilion colour. Its The analysis compared with that of the Old Almaden ore, furnished the following results to Mr. Bealey (Quarterly Journal of Chemical Society, vol. iv.): —

specific gravity is 3622.

The process by which the fluid metal is extracted is one of great simplicity. There