SELECTIONS FROM THE REPERTORY OP ARTS 1836. 
131 
SPECIFICATION OF THE PATENT 
GRANTED TO JAMES MICHELL, OF 
TRURO, IN THE COUNTY OF CORN- 
WALL, GENTLEMAN, FOR AN IM- 
PROVED PROCESS IN SMELTING 
ARGENTIFEROUS ORES. 
Sealed June 22, 1835. 
My invention consists in the processhereaf- 
ter deseribed, of submitting successive char- 
ges of calcined argentiferous ores to be fused 
with the sidphuret produced by a previous 
charge of calcined argentiferous ores in 
admixture with sulphur or with iron pyrites, 
till sufficient silver is concentrated, or where 
the argentiferous ores contain sufficient sul- 
phur, then after the first charge of uncalcined 
ore has been fully smelted and the slag 
removed, the process hereafter described of 
submitting successive charges of calcined ar- 
gentiferous ores to be reduced and concentra- 
ted by the sulphuret obtained by the smelting 
of the first charge of the furnace. 
Having thus stated the nature of my in- 
vention, I will proceed to explain the best 
manner I am acquainted with of perfoi'ming 
my said invention. The smelter having 
ascertained the composition of the various 
parcels of ore to be smelted, and having 
ascertained the best mixture which will give 
the whole when in a melting state the great- 
est degree of fusibility, all which is well un- 
derstood and commonly practised, he calcines 
the mixture so made in order to subiimate 
the sulphur and arsenic, and to decompose 
the earthy oxides this process should be 
continued till nearly the whole of the arsenic 
and sulphur are expelled. These remarks 
relate to argentiferous ores which before 
calcining do not contain sufficient sulphur 
for the first charge, and to receive subse- 
quent charges of calcined ore as hereafter 
described. 
Tile argentiferous ores when calcined are 
found better for the after process of fusion if 
left exposed to the influence of the atmos- 
phere for a week or more. 
The smelter proceeds to charge a rever- 
beratory furnace, with a quantity of the 
calcined ore (say one ton), together with the 
usual fluxes, such as lime, flour, &c. These 
are to be intimately blended with about three 
cwt. of sulphur, or otherwise with six cwt. 
of iron pyrites. This mixture is to be sub- 
mitted to an intense heat until the whole is 
brought into very perfect fusion, when the 
silver will subside from the sillicates and 
other earthy oxides, constituents of the slag, 
into the sulphuret. The slag thus freed 
from the silver is to be skimmed or tapped 
olf very carefully from the surface of the 
metallic sulphuret, taking care that as little 
as possible of the sulphuret is removed in 
the process of tapping or skimming. Ano- 
ther charge of calcined ore alone (about one 
ton), is to be put into the furnace with the 
fused metallic sulphuret produced by the former 
charge, and the whole is to be brought to a 
perfect state of fusion, the concentration of 
the silver contained in the second charge of 
calcined argentiferous ore will take place, 
the slag is again to be removed by skim- 
ming or tapping, and this process of adding 
charges of calcined argentiferous ores, is to 
be continued without further addition of 
sulphur or of iron pyrites after the first 
charge, till the smelter considers there is a 
sufficient quantity of silver concentrated, 
which he will readily ascertain by testing tlm 
slag, and when he ascertains it to contain, in 
assaying it, as much as two to two and a 
half ounces of silver to the ton, he should 
stop all further additions of calcined argen- 
tiferous ores to the fused sulphnret in the 
furnace, as the sulphuret will then be so 
charged with the silver as to materially reduce 
its powers of concentrating more from future 
charges of calcined ore, withoiit leaving the 
slags so rich of silver as to materially lessen 
the benefit of adding such additional charge 
after the slag has been found to have come 
off of the richness before mentioned. The 
charge of sulphuret is then to be tapped off 
from the furnace for a future operation with 
lead, for which purpose it must be pulve- 
rized (if it has not been granulated by tapping 
into a pit of water) and calcined, and it will be 
the better for being submitted to the atmos- 
phere for a week before submitting the 
calcined sulphuret to the further process, 
after which the lead may be added and fused 
with the calcined sulphuret in another rever- 
beratory furnace, and the silver refined by 
cupeltation as is well understood. 
It should be remarked that each charge 
should be well stirred when in a state of 
fusion, and afterwards remain some time, say 
twenty to thirty minutes, before the slags are 
skimmed or tapped off', and also that each 
successive charge of calcined argentiferous 
ores should be mixed with the usual fluxes, 
and for this purpose it will be found desi- 
rable to have a large heap of calcined ore, 
well mixed with fluxes, as is well understood. 
It will only be desirable further to remark, 
that in case the first charge of argentiferous 
ore in an uncalcined state, containing suffi- 
cient sulphur, be used in place of the applica- 
tion of sulphur to calcined argentiferous 
ore, as above described, then to the salphuret 
produced by the fusing of the same successive 
charges of calcined argentiferous ores are to 
be added according to the process above des- 
cribed. I, however, prefer using calcined 
argentiferous ores with the addition of sul- 
phur or of iron pyrites,, as above described, 
but by either means of performing the process 
considerable saving will take place in the pro- 
cess of reducing argentiferous ores. And I 
would have it understood that although I 
have stated three cwt. of sulphur or six cwt. 
of iron pyrites to one ton of calcined argen- 
tiferous ore for the first charge of the fur- 
nace, I do not confine myself thereto, but 
only state such relative proportions as the 
best I am acquainted with. 
Having thus described the nature of my 
invention, and the manner of performing the 
same, I would have it understood that what 
I claim as my invention is the process of sub- 
mitting successive charges of calcined argen- 
