The loss of lead at Clausthal, Altenau, and Lautenthal, amounts to 14 or 16 per cent; from 2 to 6 per cent of this loss is occasioned by the schlich roasting and matt smelting processes, 8 or 10 per cent by the cupelling process, and about 2 per cent by the process for reducing the litharge. The yield of silver is higher than the result of the assay by 1 or 2 per cent. At Andreasberg, on account of the large amount of antimony and arsenic in the ore, the loss of lead sometimes amounts to 60 per cent, and the loss of silver to 1 per cent.

The production of the smelting works at the Upper Hartz amounted in the year 1859-60 to 22,035 lbs. of silver, 435 tons of lead, 297 tons of litharge, and 68 tons of copper, of a total value of £193,000.

The lead produced varies in quality.

At Victor-Friedrichshütte, near Harzgerode (Lower Hartz), the smelting process differs in the following points from that used on the Upper Hartz :-The galena is worked in two forms, as schlich, and in fragments whose cubic side measurement is to 1 inches. These two kinds are mixed together; the fuel employed is a mixture of coke and charcoal, and as the ore mixture contains a small amount of metal, it possesses a basic nature. The galena contains from 32 to 34 lbs. lead, and, on an average, o'056 lbs. of silver per cwt. It is associated partly with sparry iron ore, partly with blende, quartz, and clay-slate, and partly with fallow silver ore, and with copper pyrites, which contains in 5 tons from 12 to 16 cwts. of lead, and 8 to 11.5 lbs. of silver.

Sump furnaces are used for smelting, and in 24 hours from 4 to 5 tons of ore are smelted.

The yield from 5 tons of ore is—

20 to 23 cwts. of raw lead, containing o'147 lbs. of silver; 32 to 34 cwts. of lead matt, containing 27 to 30 lbs. of lead, and o'058 to 0.066 lbs. of silver; 8 cwts. pure slags, with 4 to 6 lbs. of lead, and o'002 lb. of silver; smoke, per cent.

The lead matt is worked up as in the Upper Hartz. The annual production amounts to about 1,135 lbs. of silver, 310 tons of litharge, and from 35 to 45 tons of vitriol.

At Friedrichshütte,* near Tarnowitz, in Upper Silesia, the galenat is found partly in compact layers alternating with and disseminated through dolomite, and partly in ironochre, in lumps or grains. It is also associated with iron pyrites, calamine, and brown iron ore, and is poor in silver. The lead ores from the calamine mines are richer, and contain from o'06 to o'1 per cent of silver.

Smelting Ores in Fragments (Knorper).-This was formerly done in low cupola furnaces (Krummofen) 3 feet high, but since 1848 channel furnaces with closed eye 161 feet high have been in vogue. The higher furnaces have enabled the smelting process to be better and more regularly carried on, and have caused a greater yield of metal; they also occasion less loss of lead by volatilisation, and produce poorer slags. On the other hand, the consumption of fuel and fluxes for the process is greater, and longer time is required, but these disadvantages are outweighed by the increased yield. 100 cwts. of ore with 50 to 70 per cent of lead (often in pieces of the size of the fist) are smelted together with 19 cwts. of iron, 5 cwts. of refinery cinders, and 30 to 40 cwts. of lead slags, in 20 hours, consuming 50 cwts. of coal, and yielding—

a. 50 cwts. or so of raw lead, dependent on the quality of the ore.

b. 30 cwts. of lead matt, with about 9 per cent of lead. c. 40 cwts. of impure slags and hearth-ends.

Smelting the Schlich.-The schlich ores, containing from 30 to 44 per cent of lead, are mixed with lime; 100 cwts. of schlich and 72 cubic feet of lime. This mixture is moistened with water, and bricks are formed of it, which are allowed to dry in the air during 48 hours.

100 cwts. of schlich require 8 cwts. of iron, 24 cwts. of

* KARSTEN'S Archiv., 1 R., i., 135;vi., 170; vii., 54; 2 R., viii., 103; xxiv., 430. ERDMANN's Journal für ök. u. techn. Ch., xv., 120, 237, 392. Ann. d. Min., 1 sér., vii., 54; xii., 101; 4 sér., iv., 377; vi., 213; xiii., 271. KARSTEN'S Métallurgie, v., 157. HARTMANN's Repert., ii., 289. Bergwerksfreund, ix., 369. B. u. h. Ztg., 1852, p. 173, 470. RIVOT, Métallurgie du Plomb et de l'Argent, 1860, p. 76, 390.

+v. DECHEN, Statist. des zollv. u. nordl Deutchl, i., 757. COTTA, Erzlagerstätten, ii., 238, 708.

refinery cinders, 84 cwts. of coal, and 44 hours' time for smelting; and they yield 30 per cent of raw lead, 15 per cent of lead matt, and 50 per cent of impure slags. The operations only last 6 or 8 days, as the ores conduce to the formation of a great deal of zinciferous soot.

According to Rivot the loss of lead by volatilisation and in the slags, which are thrown away, amounts to 10'5 per cent; the loss of silver to 6'4 per cent; and the smelting cost for I ton of schlich is £1 12s. 7d.

Smelting the Residues.-5 tons require 3 cwts. of iron, 8 cwts. of refinery cinders, 22 cwts. of coal, 4 cwts. limestone, and 16 hours' time; and yield 4 to 4 cwts. of raw lead, and matt containing 2 per cent of lead, which is thrown aside along with the pure slags.

According to Rivot the yield of this process amounts to 87 per cent of the lead, and 96.50 per cent of the silver, and the smelting costs 8s. 5d. per ton.

The three processes together cause a loss of 4°48 per cent of the lead, and 14°30 per cent of the silver, and the smelting cost of I ton of ore amounts to £1 18s. 11d. The high price of the iron and cinders used makes this process expensive; and the necessity for a more perfect dressing of the ores free from silica, and enriching them from 65 to 75 per cent of lead, has been the cause of the introduction of the English reverberatory process.

In the year 1861 were produced: 1,408 tons of lead, 560 tons of litharge in lumps, 228 tons of common litharge, 57 tons of sifted litharge, and 4,179 183 lbs. of silver.

At Przibram, in Bohemia, the galena* occurs in veins in greywacke, containing from 4 to 12 ounces of silver per cwt., and is chiefly associated with zinc blende containing silver up to 6 ounces, besides real silver ores, and sparry iron ore in smaller quantities; the prevailing gangue is quartz or greywacke (up to 15 per cent), with some admixture of calca

* COTTA, Erzlagerstätten, ii., 201. GRIMM, im für, 1855, p. 93; 1857, p. 231. LILL V. LILIENBACH, gegen die Teufe im Bericht öber d. erste allgem. und Hüttenmännern in Wien. Wien, 1859, p. 12. No. 15.

Leob. u. Przibr. Jahrbach
Verhalten des Erzadels,
Versammlung von Berg
Oesterr. Zeitschrift, 1861,

reous spar and baryta. The amount of silver contained in blende makes a very careful preparatory dressing of the ore necessary, and the amount of blende and quartz in the ore, and the absence of iron pyrites, render their smelting difficult.

After many trials the following processes have been adopted for the different ores :

1. The rich lead ores are worked by the precipitation process.

2. The poorer lead ores are roasted in English and double reverberatory furnaces, and afterwards worked in cupola furnaces with iron and ferruginous substances.

3. The argentiferous blende and the poor lead ores containing blende are roasted in double muffle furnaces (vide Zinc) for the formation of sulphates and the production of sulphurous acid, which is conveyed into lead chambers for conversion into sulphuric acid.

Analysis shows the rich ores to consist of

The galena contains 77 or 78 per cent lead, and 14 per cent sulphur.

The smelting mixture is composed as follows:—

This mixture is melted in cupola furnaces. The different

smelting processes carried on at Przibram are explained subsequently.

At Joachimsthal the new smelting process is carried out as follows:-Principally silver ores are worked here,* they are mostly associated with quartz and a little lime and alumina, 5 per cent at the outside. The silver chiefly occurs in a native state, and as ruby silver ore; most of the ores contain 5 per cent of lead as galena, and some bismuth, cobalt, and nickel, combined with arsenic and iron, are present in almost all ores; iron pyrites is only rarely present. Some uranium and vanadium‡ are extracted by Patrera's method.

The first essential improvement of the former process was introduced by Vogl in his new construction of the furnaces|| which are mentioned on page 81. According to Vogl, the following expedients for avoiding a great loss of lead may be used with advantage, in addition to the new construction of the furnace :

a. The formation by protoxide of iron and lime of a basic slag, easily fusible and decomposable by acids.

b. An amount of lead in the mixture exceeding 20 per cent.

c. So large an addition of iron that the formation of deposits in the hearth is unavoidable at the end of the operation. This will cause the highest yield of silver from the smallest quantity of lead.

d. Smelting at as low a temperature as possible, with high charges, and a small pressure of blast (24 to 4 inches water), and a tuyere from 1 to 2 in. diameter.

e. An inclination of the tuyere of at least 25 degrees, and rather a dark nose.

f. Most perfect working up of the metallic soot, iron deposits, &c.

J. F. VOGL, Gangverhältn. und Mineralreichthum, von Joachimsthal Teplitz, 1856. STERNBERGER, Joachimisthaler Bergbau: Oester. Zeitschr., 1857, p. 33. J. F. VOGL, die secund. Gebilde der Joachimsth. Gruben. Oester. Zeitschr., 1856, p. 353. COTTA, Erzlagerstätten, ii. 34.

+ Oester. Zeitschr., 1586, p. 95, 230, 242; 1857, p. 40, 53. Bergwerksfreund, Bd 22, No. 37. B. u. h. ztg., 1861, p. 391.

Oesterr. Zeitschr., 1856, p. 230, 244. WAGNER'S Jahrsbericht, 1859,

P. 134.

B. u. h. Ztg., 1855, No: 1—3, 30-32. Oesterr. Zeitschr., 1857, P 51, 89; 1862, No. 5.