IMPROVEMENTS IN THE MANUFACTURE OF WHITE LEAD
Year: 1837

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
MAUGHAM, of Newport Street, Lambeth, in the County of Surrey, Chemist,
send greeting.
WHEREAS His late most Excellent Majesty King William the Fourth, by
His Letters Patent, under the Great Seal of Great Britain, bearing date at
Westminster the Fifteenth day of March, in the seventh year of His reign, did,
for Himself, His heirs and successors, give and grant unto me, the said William
Maugham, His especial licence, full power, sole privilege- and authority, that I,
the said William Maugham, my exors, admors, and assigns, or such others, as I,
the said William Maugham, my exors, adñiors, or assigns, should at any time
agree with and no others, from time to time and at all times during the term
of years therein expressed, should and lawfully might make, use, exercise, and
vend within England, Wales, and the Town of Berwick-upon-Tweed, my
Invention of "IMPROVEMENTS IN THE MANUFACTURE OF WHITE LEAD;" in which
said Letters Patent is contained a proviso that I, the said William Maugham,
shall cause a particular description of the nature of my said Invention, and in
what manner the same is to be performed, to be inrolled in His said Majesty's
High Court of Chancery, within six calendar months next and immediately
after the date of the said in part recited Letters Patent, as in and by the same,
reference being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
William Maugham, do hereby declare the nature of my Invention, and the

page_text: manner in which the same is to be performed, are fully described and ascer-
tained in and by the following statement thereof, that is to say:―
My process of manufacturing white lead, consists in converting protoxide of
lead into carbonate of lead, by passing carbonic acid gas through it, by a
method hereafter described, or by passing carbonic acid gas through a mixture
of protoxide of lead and chloride of lead. The success of the process depends
on the purity of the materials employed. I conceive it is not necessary to
describe the several processes of converting metallic lead into the protoxide, as
they are fully detailed in the different treatises on chemistry now before the
public. The mixture of chloride and oxide of lead alluded to above, is
obtained, as is well known, by acting upon a solution of common salt with
Hitharge.
To convert the protoxide of lead, or a mixture of the protoxide and
chloride of lead into white lead, the carbonic acid gas may be most conveniently
prepared by passing atmospheric air through a charcoal fire contained in a
stove closed at the bottom. The air is to be driven through the fire by an air
pump, worked by a steam engine, or by any other convenient power, a pipe
being fixed air tight so as to convey the air into the fire from the air pump;
another pipe is then-to be carried from the upper part of the furnace into a
vessel containing water, on the principle of a Woulfes bottle; the lower end of
the pipe dipping to the bottom of the vessel through the water, which is to be
kept at any convenient depth that experience will point out. This water will
allow the carbonic acid gas and nitrogen of the decomposed air to pass off,
while any impurity, such as dust, &c. will remain with the water; the carbonic
acid gas is then to be conveyed by means of a pipe just entering through the
top of the vessel in which it has been washed, (after the manner described,)
into another vessel containing the protoxide of lead, or a mixture of protoxide
and chloride of lead, mixed with clean water to about the consistence of cream
of lime, as sometimes used in purifying coal gas. This last vessel must con-
tain an agitator for the purpose of stirring up the protoxide, or the mixture of
protoxide and chloride of lead, so as to expose every particle thereof to the
action of the gas, the agitator to be worked by a steam engine, or any other
⚫convenient power.
After the process is complete, the white lead is to be freed
from the water and dried, as the protoxide of lead will not absorb the carbonic
acid gas as fast as it is driven over. The unabsorbed portion of the gas is to be
conveyed into another agitating vessel charged with protoxide of lead, or a
mixture of protoxide and chloride of lead, and water as before. It will be
necessary to have a tube of safety in the Woulfes bottle part of the apparatus
fixed in the usual manner; the nitrogen of course passes off eventually into

page_text: the atmosphere. The operator may alter or modify the apparatus above
described, that forming no part of my Invention, neither do I claim the
means described of obtaining the carbonic acid gas; it may be obtained, as is
well known by other methods, but it is most economically procured as above
described; but what I claim is the conversion of protoxide of lead, or a
mixture of the protoxide and chloride of lead into carbonic or white lead, by
the direct action of artificially prepared carbonic acid gas, as above described.
In witness whereof, I, the said William Maugham, have hereunto set
my hand and seal, this Fifteenth day of September, in the year of
our Lord One thousand eight hundred and thirty-seven.
Inrolled the Fifteenth day of September, in the year of our Lord, One
thousand eight hundred and thirty-seven.