Observations on Lead Ores. 177 
Phat of Pountaen in Brittany thirty-nine ounces. - 
Lead ore is dressed, washed, stamped, and roasted in a 
reverberatory. ; 
In Derbyshire a ton of ore is put at once into the furnace. 
Two thousand one hundred pounds of ore do not yield 
more than one thousand four hundred pounds of lead, or 
sixty-six per cent. ; 
Three tons or six thousand pounds of ore are worked 
off at a smelting house every twenty-four hours. _ 
ad ore melted by a wood fire, yields one-tenth more 
lead than by pit-coal.. (Watson IIT. 253.) 
The cupola furnace is in general use for the smelting of 
lead ores in Derbyshire ; (See Watson, III. 275,) it is a 
reverbaratory ; this furnace may be constructed any where, 
and is not noxious to the workmen. Baek Pere ag 
~ One ton is put in at a time, and three charges worked off 
in twenty-four hours ; in six hours from the charging of the 
furnace the ore becomes fluid as milk ; a bushel of lime is 
thrown in to absorb the slag, which is then raked to one 
side ; a hole, previously stopped with clay is opened, and 
the reduced metal runs out. 
By fusing the lead ore too soon, and raising the heat too 
high, much of the lead is volatilized, along with the sulphur. 
erbyshire lead is said to contain two grains of silver in 
a pound of lead. gt La are 
Mine Est Kyr-Kyr, is asserted by some, to afford sixty 
pounds of silver in every ton of lead ore; by others only four. 
There are some lead ores in Great Britain, which, al- 
though poor in lead, contain between three and four hun- 
dred ounces of silver in a ton. — 
The best kind of Derbyshire lead ore is worth £7 a ton. 
(Wet Di Sit.): eis oe ee Be 
__ Steel grained. lead ore is asserted to be much richer in 
silver than other kinds.* eae 
There is no place in Derbyshire where silver is now ex- 
tracted from lead. | a eg RE ee 
_It was done at Matlock a few years since, but is now 
abandoned, from the failure of the lead ore ;—it yielded 
fourteen ounces to a ton. ; ee 
"* See the remarks n ark on this subject, pa. 69, of the prese sent Number. : 
Vou. Hi...No bose ce a oe Ee 
