232 



MERCURY 



considerable, goes in the state of vapour into a chamber Jc ; but in passing under a 

 partition 1 1, a certain portion is deposited in a cistern i, filled with water. The greater 



1437 



part of the vapours diffused in the chamber Jtf is thereby condensed, and the mercury 

 falls down upon the two inclined planes which form its bottom. What may still exist 



as vapour passes into an upper chamber Jc' 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 up- 

 wards, 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 Tdria. 



Details of the Aludd Apparatus. 25 aludels are set in each of the 12 ranges, seen in 

 figs. 1437, 1438, 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 c, through the 

 door d, and an orifice at top ; the latter being closed during the distillation ; //are 

 vents for conducting the mercurial vapours into two chambers i, separated by a tri- 

 angular body of masonry mn; h is the smoke-chimney of the fire-place; oo are the 

 ranges of aludels, in connection with tho chamber i, which are laid slantingly towards 

 the gutter q, upon the doiible inclined plane terrace, and terminate in the chamber h q ; 

 this being surmounted by two chimneys t. The mercury is collected in these aludels 

 and in the basins at q and^>, Jiff. 1437. r is a thin stone partition set up between the 

 two principal walls of each of tho furnaces, v is the stair of the aludei terrace, 

 leading to the platform whicli surmounts the furnace ; z is a gutter for conducting 

 away the rains which may fall upon the buildings, fig. 1438. 



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 poorest species of ore, afford- 

 ing only 1 per cent, of mercury ; b, the massive sulphide of mercury, tho 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. ; /, the sands and paste called 

 echlich, 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 \)y figs. 1439, 1440, 1441, and 1442. 



