OF ARKANSAS. 191 
thus obtained is reduced toa small volume by evaporation, and an aliquot 
part of the concentrated liquid evaporated to a syrupy consistency in a 
porcelain crucible, over a water-bath. [It is not possible to evaporate the 
watery extract to dryness by means of the water-bath; the extract assumes 
the consistency and appearance of honey, without solidifying]. 
Some pure, soft iron-wire is then dissolved in strong hydrochloric acid, 
with the necessary precautions for the exclusion of atmospheric air, and 
the crucible containing the extract thrown into the solution of protochloride 
of iron; heat is applied to expel the nitric oxide, the liquid diluted with 
water, and the amount of unoxidized protoxide of iron determined by 
chameleon mineral. 
GALENA. 
In the different specimens of galena which have been analyzed, the 
amount of lead was not directly determined; but since it was proved by 
the qualitative examination of these specimens, that no other impurities, 
besides iron and silver, were present, the amount of lead can easily be 
ascertained by subtracting from 100 the sum of these impurities plus the 
amount of sulphur. 
For the determination of the silver, the following method was pursued: 
50 grammes of the finely pulverized ore are intimately mixed with 50 
grammes of carbonate of potassa, 25 grammes of cream of tartar, and 10 
grammes of metallic iron (small iron tacks); the mixture is placed in an 
iron crucible, covered with a layer of borax, the erucible closed with an 
iron lid, and then exposed to a bright red heat until the mass flows quietly. 
The contents of the crucible are then poured into a conical iron mould, 
when the metallic lead falls to the bottom, forming a well-defined metal- 
lic button which is easily separated from the slag by a blow with a ham- 
mer. The weight of the button of lead varied from 39 to 40 grammes. 
Of the metal thus obtained, about 5 grammes are subjected to cupellation, 
and the button of silver is weighed on a very delicate balance. 
The iron was determined in the following manner: The finely pulverized 
galena is oxidized with strong nitric acid; to the mass a few drops of con- 
centrated sulphuric acid are added, and heat applied until the excess of 
nitric acid is completely removed. The dry mass is treated with water, 
the insoluble sulphate of lead collected on a filter, and washed with dilute 
sulphuric acid. To the filtrate a piece of metallic zinc is added, in order 
to reduce the sesquioxide of iron to protoxide, and the amount of the lat- 
ter determined by chameleon mineral. 
