VOL. XLVl.J PHILOSOPHICAL TRANSACTIONS. 6Q1 



throw it by shovels-full into basins where there passes a current of water, and by 

 keeping it stirring, it runs over by a broad conduit descending by steps, which 

 are covered with coarse linen cloth ; and by this operation the sand is washed 

 away, and the tin remains on the cloth in form of a black scaly powder, and 

 dried is fit for melting. One hundred weight of the stone gives only 3 oz. of 

 tin; and 150 lb. of the clean washed tin mineral give 140 lb of tin. There are 

 10 melting ovens, (furnaces,) each of which can melt 9 or 10 cwt. in 24 hours; 

 the breadth of these ovens (furnaces) within side is 8 or Q inches, and from 10 

 to 12 feet long, blown by 2 pair of bellows. The proportion of charcoal to the 

 metal is nearly an equal weight. They are thrown into the oven by degrees al- 

 ternately : the residuum they melt 3 times over, which always yields new metal. 

 They make here about 800 centers per annum, which is sold from 53 to 56 Im- 

 perial gouldens per center. They find sometimes the black and sometimes the 

 white crystal mineral in nests, or clusters : the stannum polyhedron nigrum is a 

 very pure and rich tin ore : they say the white is rich also, but so hard and dif- 

 ficult to melt, that the tin is burnt to an ash before it can be brought to 

 fusion. 



Near Geffries, in Bareith, they boil vitriol. The mineral from which they 

 make it, is a black schistus, but some of it is brown. It has several small veins 

 of pyrites in it. When first taken out of the pits it has no taste ; but after it 

 has been exposed some time to the weather, and begins to moulder, it acquires 

 a very sharp taste. It is laid in great heaps, under which there are cisterns for 

 receiving the water that runs from it after rain, or that they pump on it when 

 the weather is dry. This water is conveyed by conduits into the boiling house, 

 where there are 2 leaden kettles, in which it is boiled to a strong lie, and then 

 let off into receivers where it shoots. These 2 kettles make from 8 to Q cwt. 

 per week, which is all wrought by 2 servants : it not having been found neces- 

 sary to add any new mineral to the heaps these 15 years past. But as the quan- 

 tity of the mineral consumed in that time, is not known, it is impossible to de- 

 termine how much of this salt has been supplied by the air. They only add to 

 the quantity -l cwt. of iron, which is consumed in the kettles every week, and 

 makes it shoot into copperas : but instead of this, if they add copper, it makes 

 blue vitriol. Formerly they made alum here likewise from the same lie, only 

 instead of iron or copper, they added potash and urine : but the expence of the 

 first, and the difficulty of getting the other in sufficient quantity, has made them 

 leave off making alum here for some years past. [Then follows an account of 

 the salt mines near Cracow ; but as descriptions of these celebrated mines are 

 given in numerous books of travels and geography, it was deen>ed unnecessary 

 to reprint it in this collection.] 



V 



4 t2 



