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owing to its convenient situation near the three main shafts of the mine ; secondly, because a good connection was afforded by the main railway-line of Halsbriicke, Freiberg, and Mulden-Hutte, this line having been specially built in the interest of the Freiberg mines and smelting-works. The washer was built between the two main hauling-shafts (Abraham and David), thus at the time facilitating a good communication with the Thurmhof and Beiche Zeche (shafts). All the shafts are connected with the plant by a narrow-gauge railway. The chosen site is near the watershed of the Bivers Mulde and Miinz, on the slope of the Mulde Valley. " Steam alone may be used as the motive-power, whilst the water for washing purposes comes from the water-channel of the Himmelfahrt Mine, which is one of a network of channels which have been carried from one mine to the other; but, owing to this supply being very irregular, especially as the late summers have been very dry, and as no work is carried on at night, it has become necessary to construct a reservoir containing about 10,000 cubic metres—that is, 350,000 cubic feet, or 2,182,425 gallons. This reservoir, which is kept full by the above water-channel, supplies in its turn water for washing purposes and for the boilers. The dimensions of the reservoir are such that, should the water-supply be entirely cut off, it would take, if used for washing purposes, two and a half weeks to empty it, at the rate of 35 cubic feet per minute, or 21,000 cubic feet per day of ten hours. " The maximum quantity to be worked was taken at 1,500 double centners, or 150,000 kilograms—equal to about 140 tons—consisting of milling- and stamping-ore. The above quantity was decided on, partly with a view to the possible increase in the supply of ore, and also to allow of the working of poorer classes of ore by means of a rational and cheap washing process; it was also arranged that ore of different silver-value could be worked separately in the same plant. The yearly average output of the Himmelfahrt Mine is 450,000 d.ctr., or about 44,300 tons of crude ore, of which four-fifths come from the veins of the so-called pyritic lead formation, and one-fifth from those cross-veins where brown and heavy spar occur, and where, especially on the crossings, native silver occurs, together with galena rich in silver. The latter is evidently a mechanical mixture, but at the same time chiefly a microscopical one. This one-fifth is for the most part worked separately by the dry process, hand-separation, and dry stamps, so that the four-fifths which passes through the washer may be estimated at not more than 360,000 d.ctr. per year, or 1,200 d.ctr. per day, equal to about 118 tons per day. From the above quantity a certain number of tons have also to be deducted, resulting from the rough hand-separation, shipping ore, and waste. The capacity of the plant therefore allows, if necessary, for the treatment of ores from the other fiscal mines. Particular stress is laid upon the fact that the plant is arranged on a double system, so as to allow for the separate working of ore from different veins or districts. " The ore to be concentrated undergoes in the first place a rough hand-separation, and consists mainly of milling- and stamping-ore—that is, a more or less intimate combination of galena, iron, and arsenical pyrites, copper-pyrites (seldom), zinc-blende, gangue (gneiss), part containing quartz, part spathic gangue. The different minerals are in a partly fine but mostly in a coarse combination. In many of the ores galena predominates, but in most iron-pyrites occur as the most plentiful component next to the gangue. The value of the galena in silver generally varies between 0-15 to 0-17 per cent., and reaches 0-20 per cent, in some veins—that is, 490z. to 550z. lOdwt. 16gr. in the former, and 650z. 6dwt. 16gr. in the latter. The small-grained galena is, as a rule, the richest in silver. Arsenical pyrites occur in some of the veins of the Himmelfahrt Mine, and it contains no silver. This mineral is separated as an ore of arsenic. Iron-pyrites do not contain any silver, and predominate in most of the veins. Copper-pyrites occur but seldom, and then, as a rule, in the form of small pockets in massive galena. It is shipped, together with the latter, as lead-copper, with 3to 4 per cent, of copper. The zinc-blende is the well-known Freiberg black zinc-blende, containing up to 33 per cent, of iron, having a specific gravity nearly the same as the accompanying iron-pyrites. On this account, the separation, even with the best and most careful classifying of the grains, and the best-arranged jigging, becomes exceedingly difficult. The separation of the zinc-blende ores is therefore, begun in the mines, and is also carefully carried out on the surface by hand-separation, so that the accumulated blende ores may be worked as far as possible by themselves. " The Main Principles of the Plant. " The main principles, which have been carried out according to the nature of the ores to be treated, and to the cheapness of working, are as follows : First, the ore should be disintegrated step by step, and the different substances should be immediately collected after each disintegration, in order to prevent loss of metal and power, by doing away with unnecessary crushing. This principle was recommended by the author in his report to the Government in 1885. Secondly, the greater portion of the crushing and concentration should be done by the rolls and coarse jiggers, and as small a quantity as possible by the stamps, small jiggers, and slime apparatus, as the loss is always greater in the latter. Thirdly, the work should be continuous from the beginning to the end, as well in the coarse-grained ore as with the fine, so that all intermediate transport and accumulation of material may be avoided. By carrying out these principles, the saving of silver and lead is increased, and the hand-labour and the whole cost of treatment is greatly diminished. To obtain an automatic working of the process, as the slope of the hill could only be utilised for the lower part of the plant (the slime-works), the main building, consisting of rolls and jiggers, had to be built in several stories. It was also necessary to excavate nearly three-fourths of the ground, that is—19,375 square feet —for the main building, and one-fourth, that is—8,224 square feet—for the slime building. In the jigging work less stress has been laid upon the too exact carrying-out to decimals of the sizing of grains ; but a more important matter is that the superficial area of the appliances be sufficient to effect a thorough separation. Much care is taken in the treatment of the fine grains (sand and pulp) before they are allowed to be worked on the slime-tables. As previously mentioned, to allow of the working of ores of different