Ihc 0?iicJiyilver Mines of Idria in Ilbjna. 341 



The first, wliich is destined to roast the ores in large pieces, 

 ?ias in the first place a trape/.ion fire-place, surmounted by a 

 sort of open vault or chimnev, which conuiiunicates with a kind 

 of furnace into which the charge of the ore is put. Care is taken 

 to supply this first vault with poor ores in large pieces, in order 

 afterwards to be able to charge it witli all the fiagmcnts which' 

 are richer. This furnace once well filled, the second furnace, 

 which is superposed on the first, is charged ; its vault is also open 

 at top, and its hollow ])art is formed bv the vault or chimney of 

 the lat.ter. Instead of charging this second vault wiih ores in 

 pieces of a certain size, it is charged with lumps of earth into 

 wliich small ores have been put called gruben kie'ni, or tlie va- 

 rieties which we have called kernvo. This last furnace being- 

 charged, the doors of all the chambers are luted. 



This first furnace has tuo fronts, ?'. e. two fire-places, and four 

 chambevs, which communicate by lateral pipes with two rows of 

 reservoiis of mason work, or very high chambers separated by 

 intermediate walls, but communicatirig with each other l)y aper- 

 tures of .T. square foot, placed alterntilely. The number of 

 these reservoirs or condensers is twenty-eight. The area is in- 

 clined, in order to facilitate the flowing of the mercury into re- 

 sej'voirs destined to receive it. The last of these chambers of 

 condensation is surmounted by a second chamber above the first, 

 which is terminated bv a chimnev to give vent to the vapours 

 that cannot be condensed in this large apparatus. A funnel 

 common to all the reservoirs facilitates the arrival of the mer- 

 cury in another large reservoir in tlie apiutment where the mer- 

 cury is collected in order to pack i!;. 



The second furnace destined to burn all tlie ores in powder is 

 constructed on the same principles, with this difference only, 

 that there are six fmnaces instead of four, and twenty- four 

 chambers of condensation instead of twenty-eight ; and tlie fur- 

 naces are charged with lumps of earth filled v.'itli sclilitcks, or 

 ore in powder. 



In the first-mentioned fiu'nace only 300 quintals (cwt.) of ore 

 are burnt, and in the second the charge may be (iOO quintals and 

 upwards. 



Tlie charge of the ores when once effected, all the apertures 

 both of the (urnaces and of the chani!)ers of condtMisation are 

 carefully luted with clay and slacked linie ; afterwards the whole 

 is heated for about nine hours with a progressive fire, until the 

 earthen clods are red hot, and the ores in pieces burn vehe- 

 mentlv. This time is generally sufficient. The apparatus is 

 then allowed to cool for six days, and the mercury is afterwards 

 collecteil. It would be dilficult to obtain the metal sooner, as 

 the furnace retains its heat a long liuic. 



Y 3 One 



