A METHOD OR METHODS OF MAKING SOFT LEAD OUT OF HARD LEAD OR SLAG LEAD
Year: 1816

page_text: TO‘ALL' TO WHOM THESE PRESENTS SHALL COME, I, Walter
HALL, of Serjeants Inn, in the City of London, Merchant, send greeting.
WHEREAS His present Majesty King George the Third, in and by His
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Twenty-first day of November last, (after reciting that I, Walter
Hall, had, by my petition, humbly represented unto His said Majesty that in
consequence of communications from certain foreigners residing abroad I was
in possession of "A METHOD OR METHODS OF MAKING SOFT LEAD OUT OF HARD
LEAD OR SLAG LEAD," and that such method or methods was or were entirely
new in this country, and that the same had never been practised or used by
any person or persons in this country to the best of my knowledge and belief,)
did, for Himself, His heirs and successors, give and grant unto me, the said
Walter Hall, my exors, adñors, and assigns, His especial licence, full power,
sole privilege and authority, that I, the said Walter Hall, my exors, admors,
and assigns, and every of them, by myself and themselves, or by my and their
deputy or deputies, servants cor agents, or such others as I, the said Walter
Hall, my exors, adñmors, or assigns, should at any time agree with, and no
others, from time to time and at all times thereafter, during the term of years
therein expressed, should and lawfully might make, use, exercise, and vend my
said Invention within that part of the United Kingdom of Great Britain and

page_text: Ireland called England, the Dominion of Wales, and Town of Berwick-upon-
Tweed; in which said Letters Patent there is contained a proviso that if I, the
said Walter Hall, should not particularly describe and ascertain the nature of
my said Invention, and in what manner the same is to be performed, by an
instrument in writing, under my hand and seal, and cause the same to be
inrolled in His Majesty's High Court of Chancery within six calendar months
next and immediately after the date of the said Letters Patent, that then the
said Letters Patent, and all liberties and advantages whatsoever thereby
granted, should utterly ceasc, determine, and become void, as by the said
Letters Patent, reference being thereunto had, will more fully appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Walter Hall, do hereby describe and ascertain the nature of my said Inven-
tion, and in what manner the same is to be performed, by the following
description thereof (that is to say) :-
The method of calcining lead is well known and understood, as is also the
method of making red lead. My Invention consists in stopping the calcination
of the hard or slag lead after a certain proportion has been calcined. For
example: put thirty hundredweight of hard or slag lead into an oven or
furnace of the sort employed in calcining lead for red lead. Calcine a propor
tion of such hard or slag lead, and after such proportion is calcined draw from
the oven or furnace that part of the hard or slag lead which is uncalcined, and
the same will be found to be soft lead. The proportion of the hard or slag
lead which I calcine I find to vary in general from three hundredweight and
one half of a hundredweight to five hundredweight in every twenty hundred-
weight of the lead or slag lead, but the proportion to be calcined must depend
on the quality of the hard or slag lead put into the oven or furnace for cal-
cination; and therefore I do not mean to confine myself to the proportion
specified. The proper proportion, however, may be ascertained while the
process of calcination is going forward by the following method:-Draw from
the oven or furnace about twenty-eight pounds weight of lead, or any other
convenient quantity out of the quantity therein, and cast it into an ingot, and if
a sufficient quantity of the hard or slag lead originally put into the oven or
furnace have been calcined, the quantity so cast will exhibit the usual varie
gated colours which good or soft, lead has when melted, and will have lost its
ringing quality; but if it do not exhibit the usual variegated colours, and have
not lost its ringing quality, then a further part of the hard or slag lead must
be calcined, until by the same trial as before it be ascertained that the lead does
exhibit the said colors, and has lost its ringing quality. The part of the hard

page_text: or slag lead which has been calcined, I reduce to lead according to the ordi-
nary process, and use it as hard lead; but this is no part of my Invention.
In witness whereof, I have hereunto set my hand and seal, the Seventlı
day of May, in the year of our Lord One thousand eight hundred and
seventeen.