4i6 BOOK IX. 



by agitation ; when taken out they are broken up with a square iron mallet, 

 and then they are re-melted with the fine tin-stone next smelted. There 

 are some who crush the slags three times under wet stamps and re-melt them 

 three times ; if a large quantity of this be smelted while still wet, httle 

 tin is melted from it, because the slag, soon melted again, flows from the 

 furnace into the forehearth. Under the wet stamps are also crushed the 

 lute and broken rock with which such furnaces are hned, and also the 

 accretions, which often contain fine tin-stone, either not melted or half- 

 melted, and also prills of tin. The tin-stone not yet melted runs out 

 through the screen into a trough, and is washed in the same way as tin- 

 stone, while the partly melted and the prills of tin are taken from the mortar- 

 box and washed in the sieve on which not very minute particles remain, and 

 thence to the canvas strake. The soot which adheres to that part of the 

 chimney which emits the smoke, also often contains very fine tin-stone which 

 flies from the furnace with the fumes, and this is washed in the strake which 

 I have just mentioned, and in other sluices. The prills of tin and the partly 

 melted tin-stone that are contained in the lute and broken rock with which 

 the furnace is Uned, and in the remnants of the tin from the forehearth and 

 the dipping-pot, are smelted together with the tin-stone. 



When tin-stone has been smelted for three days and as many nights in a 

 furnace prepared as I have said above, some little particles of the rock from 

 which the furnace is constructed become loosened by the fire and fall down ; 

 and then the bellows being taken away, the furnace is broken through at the 

 back, and the accretions are first chipped off with hammers, and afterward 

 the whole of the interior of the furnace is re-fitted with the prepared sand- 

 stone, and again evenly Uned with lute. The sandstone placed on the bed 

 of the furnace, if it has become faulty, is taken out, and another is laid down 

 in its place ; those rocks which are too large the smelter chips off and fits 

 with a sharp pick. 



Some build two furnaces against the wall just hke those I have described, 

 and above them build a vaulted ceihng supported by the wall and by four 

 pillars. Through holes in the vaulted ceiling the fumes from the furnaces 

 ascend into a dust chamber, similar to the one described before, except that 

 there is a window on each side and there is no door. The smelters, when 

 they have to clear away the flue-dust, mount by the steps at the side of the 

 furnaces, and chmb by ladders into the dust chamber through the apertures 

 in the vaulted ceiUngs over the furnaces. They then remove the flue-dust 

 from everywhere and collect it in baskets, which are passed from one to the 

 other and emptied. This dust chamber differs from the other described, in 

 the fact that the chimneys, of which it has two, are not dissimilar to those 

 of a house ; they receive the fumes which, being unable to escape through the 

 upper part of the chamber, are turned back and re-ascend and release the 

 tin ; thus the tin set free by the fire and turned to ash, and the httle tin- 

 stones which fly up with the fumes, remain in the dust chamber or else adhere 

 to copper plates in the chimney. 



