The Emporia news. [volume] (Emporia, Kan.) 1859-1881, 1878-06-21
While Lead.

White Lead.
By far the most important article
In the paint trade is carbonate OF
lead, or, as IL is more commonly
called, white lead. This importance
results from the fact that it consti-
tutes the body not only of white
paint, but OF all the best paint of
every color or shade that is used.
A great many other articles have
been tried, but nothing else found
b to remain 30 permanently as the
smooth hard coating, which at once
RI gives beauty and defies wear-the
two objects for which we paint.
Every one Is familiar with the mis-
cradle powder, which, after little
time, remains on the outside of our
houses to be brushed of, or the
great patches of paint that peel of,
where some inferior article has
been used. Though costing more
at first, 1t is true economy to use
good lead and good ell when we
paint.
The manufacture of white lead
was the discovery of the Dutch q
long time ago, and though made to
shorten and improve the process,
owing to certain natural limitations,
It has never been essentially chang
ed where the production of the best
article was required. This process
probably varies somewhat in detail
in different establishments, but yet
it remains substantially the same as
at first introduced. 1t requires the
purest metallic lead, which is either
cut or cast into such forms as to
present the largest surface to the
action of the acid. Formerly it was
cut into spiral coils, perhaps quar-
ter of an inch thick, and Of such
size as to fit into the top of small
Z searthen vessels like q flower pot.
Lately it is more generally cast into
very thin CRATES or buckles, five or
six Of which are laid within the
pot upon q small projection made to
receive them. In the bottom of the
pot, but 80 as not to touch the lead,
is small quantity of acetic acid or
vinegar. Pots thus prepared are
placed in rows upon a convenient
area, perhaps twenty or twenty-five
feet square; bed of spent tan
bark foot thick, it may be, being
spread beneath them. When the
area has been covered by rows of
pots, thin sheets or strips of lead
are laid upon the top; a small piece,
however, being either broken out
of the edge of each pot, or left out
in making it, so as to give Q free
circulation of air or gas from one
to another of the whole number.
Over these rows, as thus arranged,
is now placed covering of planks,
on which is placed another bed of
tan, and upon it arranged another
series of pots just like the former.
Aud so, layer after layer, is built up
. stack some twenty-five feet high,
the sides of which are held in place
by frame and planking. The stack
has not been long completed before
the tan begins to heat and the fer
mentation raises the Temperature
within to 140 degrees or more, and
so turns the acetic acid within the
pots into Yapor. This rises and at
tacks the strips of lead which haye
already begun to oxidize; and thus
is formed the thin film of another
compound called the subacetate of
lead. But the fermentation of the
tan has by this time begun to give
out freely carbonic acid, which,
reaching the subacetate, draws to
itself the fine particles of lead which
1t contains, and SO leaves the acid
free to attack the metallic lead: be-
meath, as 1t did before. This simple
chemical process goes on for three
months or more, till the power of
the tan is exhausted, so that it can
no longer keep up the fermentation,
when the stack Is taken down, and
. most wonderful change is found
to have taken place within the pots.
The strips Of lead retain their form
indeed, somewhat increased in size,
but they are changed in color to q
most beautiful white. The surface
crumbles freely, and the fragments
are rubbed without difficulty to the
finest powder. This transforma-
ton in some cases has gone all
through the original metal; but in
others q core is left in the center, of
hard blue lead,' which has not
been changed. The difference thus
found to exist will depend on va
rious circums tances, such as moist
ure of the atmosphere, temperature,
position in the stack, strength of the
tan, &c. II these cores exist, how
ever, the next process Is to separate
them, and reduce the white lead to
fine powder. This is accomplished
the pieces of carbonate, as taken
from the pots, between rollers in
others, by breaking them by Other
means and, in any case, screening
away the blue lead after which the
white lead is ground in water be,
tween mill stones, the process being
repeated till the paste is as ilne 81
it possible to be made. The rem4in
n n ~ In, N
Grating the water; which is done il
many establishments in large cop
per pans having two bottoms be
tween which the exhausted steam
from the engine is passed. Other
have different arrangements; but
however accomplished, when tn,
drying is complete, the powder Il
ready to be packed for the market
twill be readily seen that tn,
manufacture of white lead take
much time, and involves the outla,
of large capital. A single stack
will sometimes contain fifty or six
ty tons of lead, distributed amons
some twelve thousand pots; and, t
keep the works in operation, Their,
must be several stacks, the work
men building some while others arr
fermenting. Some establishment
have as. many as 10000 pots.
The grinding of paints in oil is ,
distinct process, and is carried OIL
mainly by q different class of man
ufrcturers. In this there is mucI
adulteration of the lead, as we'll Al
the mixing of various coloring mat.
tiers for making the colored paints
Some English manufacturers Of IN.
ground white lead, too, adulteratG
the article they export, trusting thai
1ts,being sent so far. away, will
shield them from responsibility
But our best Like
the Brooklyn White Lead Compa.
ny-could not afford to do this, ev.
en- il they desired, as their custom
depends so largely on their reputa.
ton for truthful dealing. Those
who supply exactly the article or
dered, whether IL be pure white
lead, or mixture, of that article
with zinc white, sulphate of barry
ties, or other Ingredients (Which
wrnf~tnHna ~