Chinese process for making Sheet Lead. 391 
to one of the primitive planes, viz. that which is the least 
easy to obtain by cleavage. Several of the forms greatly 
resemble some of the varieties of feldspar, being composed 
of the same number of planes disposed in the same manner, 
and it is only by using the Goniometer that the difference 
can be perceived. Notwithstanding this great anology, Mr. 
Levy believes that the forms of the two substances are in- 
compatible. He considers the primitive of feldspar to be 
an oblique rhombic prism, and not a doubly oblique prism, 
as ithad been supposed by Haity, and he takes for the prim- 
itive of Cleavelandite a doubly oblique prism. The crys- 
tals of Cleavelandite are generally white, sometimes yellow- 
ish and reddish. They are transparent, sometimes translu- 
defined crystals. The localities of Cleavelandite are very 
numerous, and this substance seems likely to become one of 
the most important both in mineralogy and geology. All 
the rocks of which feldspar is considered as a component 
part, must be re-examined to separate those which really 
contain feldspar, from those which contain Cleavelandite. 
he localities derived from Mr. Turner’s collection are the 
following : Daupbiny, St. Gotbard, Tyrol, Piedmont, Bave- 
no, Elba, Vesuvius, Saxony, Sweden, Norway, Siberia, 
Greenland, United States, and Rio Janeiro. 
An. Philos. Nov. 1823. 
27. Chinese process for making sheet lead.—The reduc- 
tion of lead into thin sheets, is done by two workmen, one 
seated on the ground, having before him a large flat stone, 
very smooth, and holding in his hand another flat stone, a 
kind of muller; along side is a furnace in which is placed a 
crucible filled with lead. A second workman pours upon 
the stone, a quantity proportioned to the size and thickness 
of the intended sheet, and the other pressing his muller for- 
cibly upon it, produces a leaf which is very thin, and of an 
equal thickness throughout. It is immediately removed and 
the operation repeated with extraordinary rapidity. hen 
& certain number of sheets are obtained, they trim the bor- 
ders which are always ragged, and tie them together. 
