The Placer herald., 1872-03-02
Written for the HERALD.
METALS-THEiR ANTIQUITY AND USES
No. G.-TIN. lConcludea.l

LIN ana icad, IN varying pfop9flClls, con-
stitute a species Of pewter, and one part of
tin with two of lead forms plumbers solder
The best kind Of pewter, for engraving music
on, is made of tin and antimony. The most
important application of tin to ihe covering
of other metals is employed in the manu-
tacture OF tin-plates; of which numberless
articles used in the daily business Of life,
especially for culinary purposes, are so neatly
and so cheapy made. The process is inter
esting enough on all accounts to merit de-
scripton in detail. The latten, or plates to
be timed, are made from the best Welsh
iron, or iror of the best quality, which have
been redt Il from the ore by means of char
coal instead of coke. This is rolled out
into plates three-eightbs of an ;Nch thick
These plates are then cut in pieces, ten inches
long by six inches wide, which are repeat
edly heated and rolled until reduced as thin
as required Each sheet thus formed is
then doubled and rolled again, tEen doubled
again and the rolling repeated. The jagged
edges are then cut off by stout shears, and
The quadrupled plate reduced to a certain
size. 1t Is then cut across, ard the eight
pieces being ripped asunder, are piled in
heaps; 225 plates constitute what is called
box. Another workman then bends the
plate across the middle, so that it resembles
in its profile the letter U. The plates are
next stepped in diluted muriatic acid for four
or five minutes, and, when dried, are placed
in a reverberatory furnace, where the heat
causes a thick scale to come off; the form Of
the bent plate, set on its double edge, allow
ing the heat to get equally at both sides,
which it would not do had the plates been
laid flat in the furnace When cold they
are beat flat again on cast iron block, and
then rolled between hard, polished, steel
rollers, screwed so tight that The utmost
pressure is exertcd on the plates. BY this
operation they are made perfectly fiat, smooth
and elastic. The plates are next placed in
houghs containing water in which bran has
been stepped for nine or ten days, so as to
acquire sufficient acdity. In this ley they
remain for ten or twelve hours. The next
operation, termed picking, consists in i'm
mersing the plates for about an hour in di
luted sulphuric acid, contained in leaden
trough divided by partitions, each division
holding box Of plates. A fue passing
under the trough by heating the liquid has
tens the action of the acid, which makes the
plates perfectly bright A strong vessel of
cast iron, capable Of holding two or three
hundred Of these sheets OF iron and about
five hundred weight Of tin, is fixed so as to
be heated by fire from beneath, and by
Aues which 20 around it. This bath is nearly
filed with Il mixture in equal proportions Of
block and grain tin, and quantity Of tallow
is added, sufficient TO cover the surface of
the metal when melted, to the depth of four
inches The use of this grease is to preserve
the molten tin from oxydiyng by the action
of the air, and it is found that it also assists
the union Of the two metals. Previous to
timing the plates are immersed for about an
hour in another vessel filed with melted
grease only, and they are then dipped into
the bath Of tin edgewise, where they remain
for an hour or an hour and Il half. The
plates are then taken out with Il tongs and
placed on an iron rack for the superiuous
tin TO drain from them. Bat even after this
process there is twice as much tin left on the
iron as is necessary, and to remove this is
the object Of the next operation, called wash
ing. -Four more iron trQughs, Of the same
lengths and depths Of the first, but of differ
ent widths, are, like that, set over hues, on
a brick foundation, so as 10 lie at conve
nient height for the workman. The first pot
is filled with the best grain tin only, melted;
the second with clean taow; the third has
only an iron grating at the bottom to receive
the plates, and the last has small quantity
of melted tin in it, sufficient to cover the
bottom to the depth Of quarter Of an inch.
The workman puts the plates which have
been timed into the wash-pot, when the
heat of the melted tin in it soon dissolves all
the loose metal on the surface. lie then
takes out the plates singly, and, holding
them in a pair of tongs with one hand,
brushes the two sides with hemp brush Of
IA particular kind TO remove the superfuous
metal. Again he dips the plate into the tin.
and Withdrawing it instantly, plunses it in
the trough with the grease i'll it, in which it
only remains long enough to remove the
extra tin. The second dipping in the metal
after brushing is intended to remove the
marks of the brush, and to equalize the
coating; but as this dipping causes too great
a quantity of metal to adhere to the surface,
the grease is intended again to separate this
surplus quantity. They are then left in the
trough with the grated bottom, to cool, this
vessel having no hue under it; but as they
stand upright in the trough, the tin, before
it hardens, subsidies little to the bottom
edge and forms a rim, list, along it. The
metal thus collected in greater thickness at
this part must be saved, and this is done by
an assistant, called a list-boy, who dipping
the edge into the shallow fluid tin in the
last, Or list-pot, and the heat re-meltng the
suLsided metal, it runs Off on smart blow
being given the plate as it is Withdrawn.
The plates are finally cleansed from the