328 Manufacture of Suiphat of Iron. 
and copper with an excess of acid. During the process of 
evaporation a leaden vessel, having its sides perforated and 
containing fragments of old iron is suspended in the liquor. 
The iron at the same time that it neutralizes the excess of 
acid, decomposes the sulphate of copper and the copper is 
precipitated in the form of a fine powder which the work- 
men call “copper mud.” In a conversation with Profes- 
sor Cleaveland upon this subject he observed, that he could 
conceive why the copper did not form a pellicle upon the 
iron. ‘T think its detachment is referable to the constant 
and active operation of the acid in the hot liquor, removing 
the copper as fast as it is deposited. Hydrogen gas which 
I collected in tumblers and burned, is evolved during 
the solution of the metallic iron in the acid liquor. When 
the liquor is first heated it becomes turbid with some earthy 
material, probably alumine. 
After the liquor has been -suficienly evaporated it is 
drawn off into cisterns to crystalize. Branches of trees are 
put into them as a nucleus for the crystals. When the 
rystalizati s -as far as it will gO, the remain- 
in fluid i is drawn off, and returned to the evaporating ves- 
sels. The cistern remains lined several inches in thickness 
with crystals, like a geode. The branches have a fine crop 
of foliage and fruit composed of beautiful green crystals. 
‘The crystals are very large and perfect, ame numer- 
ous brilliant facets which are often several inches broad. I 
obtained 
. rl bas : 
° ~ Every thing about this mineral’ manufactory is curiously 
with iron rust. When a dry day succeeds a rain 
or ashower, the whole mine becomes covered with a white 
erystalline efflorescence like a hoar frost, and the rain water 
which runs down into the cavities of the mine becomes so 
strong a solution as to crystalize. Wherever the solution 
istinguished fr om them: were it not for 1 
se sti mero: at some 
“seasons and present a very beantiful | spectacle. 
Spr ene as method has been contrived et de 
wash of the whole mine. There has been cut in the com- 
t ore, quite across the lower edge of hie oan Ce 
