A PREPARATION OF SULPHATE OF LEAD APPLICABLE TO SOME OF THE PURPOSES FOR WHICH CARBONATE OF LEAD IS NOW APPLIED
Year: 1839

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
RICHARDSON, of the Town and County of the Town of Newcastle-upon-Tyne,
Chemist, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Ninth day of December, in the third year of Her reign, 'did,
for Herself, Her heirs and successors, give and grant unto me, the said
Thomas Richardson, Her especial licence that I, the said Thomas Richard-
son, my exors, admiors, and assigns, or such others as I, the said Thomas
Richardson, my exors, admors, or assigns, should at any time agree with, and
no others, from time to time and 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, and also in all Her
Majesty's Colonies and Plantations abroad) my Invention of "A PREPARATION
OF SULPHATE OF LEAD APPLICABLE TO SOME OF THE PURPOSES FOR WHICH CARBONATE
OF LEAD IS NOW APPLIED;" in which said Letters Patent is contained a proviso
obliging me, the said Thomas Richardson, by an instrument in writing under
my hand and seal, particularly to describe and ascertain the nature of my
said Invention, and in what manner the same is to be performed, and to
cause the same to be inrolled in Her 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.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
Thomas Richardson, do hereby declare that I use the term sulphate of lead
in the common and popular sense, thereby meaning a combination of sul-
phuric acid and protoxide of lead; and I do not use it in any purely scientific
sense, as denoting the particular combination, viz, one atom of sulphuric acid
to one atom of protoxide of lead) to which chemists now confine it; that the
nature of my said Invention consists in the use of acetic lead and the prot-
oxide of lead with sulphuric acid, so as to produce a combination of sulphuric
acid with protoxide of lead, the said combination having a body, and which
body renders it applicable to some of the purposes to which carbonate of lead
is now applied. And I may generally explain that the term "body" here
used denotes that quality which enables a substance used as a paint to cover
effectually the surface of anything to which it is applied.
The manner in which my said Invention is to be performed is as follows:-
I use protoxide of lead as it usually occurs in commerce, and prefer what is
known as flake litharge, which is put into the tub herein-after described, where
it is mixed with a quantity of strong acetic acid, in the proportion and of the
strength after mentioned, and a quantity of pure water sufficient to render the
whole moist. The mixture thereof is effected by the agitation herein-after
explained, which is continued sufficiently long to enable the acetic acid to act
upon the protoxide of lead, and to convert a portion of it into an acetate of
lead. I use acetic acid of the specific gravity 1.046, or thereabouts, in the
proportion of one part to fifty-six parts of protoxide of lead; and I operate
upon one ton of litharge. This proportion is the most economical, but a
larger proportion of acetic acid may be used. The agitation is continued, and
when a portion of the protoxide of lead is converted into acetate of lead, I
begin to pour into the tub through a leaden or other convenient part-sulphuric
acid of the specific gravity 1-5975, or thereabouts, at the rate of about one
pound per minute, until a quantity of sulphuric acid has been added sufficient
to convert all the protoxide of lead into a sulphate of lead. This quantity
must be in the proportion of twenty parts absolute sulphuric acid to one
hundred and twelve parts of protoxide of lead; but the proportion of sulphuric
acid may be increased. to forty parts. The agitation is continued until the whole
of the protoxide of lead has combined with the sulphuric acid added, when
the sulphate of lead thus formed is removed to a convenient trough, where it is
washed free from the foreign substances; after the washing is finished it is
ground in water, and then dried in stoves similar to those already in use in
manufactories of white lead. This sulphate of lead thus made will possess a
body, and is applicable to some of the purposes for which carbonate of lead

page_text: is now applied, to wit, painting, glazing pottery ware, &c. The apparatus
which I recommend to be used for the agitation herein-before described is as
follows, viz, a circular wooden tub or vessel, as shewn in the Drawing
annexed, of the depth of about two or three feet, and about six or seven feet
in diameter, completely lined with sheet lead, and covered by a lid. This
vessel should be raised a convenient height from the floor of the apartment in
which it may be placed, so as to allow the machinery for agitating the mate-
rials sufficient working space underneath. In the centre of the bottom of the
vessel should be fixed, pointing upwards, and perfectly water-tight where it
joins the leaden lining, a leaden tube or boss E, E, about eighteen inches
high, and of a diameter sufficient to allow an upward shaft F to pass through.
This upright shaft F is fixed in the ground in the floor of the apartment, in
a footstep, so as to be easily moveable, and passes up through the bottom of
the wooden tub, through the tube or boss E, nearly to the lid of the tub, into
a bar of wood fixed across the tub to steady the motion. Near to the top of
the shaft F are fixed three horizontal arms of iron L, L, at equal distances
from each other, reaching to within about two inches of the sides of the tub.
Into each of these arms are inserted and fixed, by means of screws, two iron
rods M, M, reaching to within about an eighth of an inch of the bottom of
the vessel. To the ends of the rods are fixed thin iron plates N, N, about
two inches broad, and of a length to reach from one eighth of an inch to the
side of the tub, to within one eighth of an inch of the leaden boss, and sloping
forwards at an angle of about 25° or 30° to the bottom of the tub. The
whole of the machinery inside the tub must be covered with sheet lead to
protect the same effectually from the action of the acids. The upright shaft
F is made to revolve by a bevel cog wheel fixed near to its lower end, working
into another bevel cog wheel attached to a shaft worked by steam, or any
other power, by which means the machinery is made to revolve inside the tub
and agitate the materials in a very perfect manner.
Now I do not claim as my Invention any particular form of vessels or
apparatus in which or with which-my operations may be conducted; and I
consider the proportions of the ingredients herein-before stated to be the best
adapted for carrying my process into execution, although a larger proportion
of acetic acid would facilitate the process, and might on some occasions be
usefully adopted to save time, but for the economical purposes of commerce I
find the above proportions the best; but any proportions will do so long as
the quantity employed of acetic acid is not sufficient to convert all the prot-.
oxide of lead into an acetate of lead of any kind; nor do I confine myself to
the quantity of water employed, but consider a moist state as the state in
which the whole is best mixed.

page_text: As respects the use of acetic acid in the aforesaid process, I have also to
notice some other substances which may be employed instead of free acetic
acid in my process. For example, acetate of lead may be used in such pro-
portion as to afford the same relative quantity of acetic acid, and in such case
the agitation is required merely to mix intimately the ingredients; or acetate
of soda can be used for the same purpose, introducing as much acetate of soda
instead of acetic acid as contains the requisite quantity or proportion of the
acid. It is highly probable from our chemical knowledge that other acetates
may be usefully employed, but the above mentioned are those which alone I
have tried.
And such my Invention being, to the best of my knowledge and belief,
entirely new, and never before used in that part of Her Majesty's United
Kingdom of Great Britain and Ireland called England, Her Dominion of
Wales, or Town of Berwick-upon-Tweed, I do hereby declare this to be my
Specification of the said Invention.
..
In witness whereof, I, the said Thomas Richardson, have hereunto set
my hand and seal, the Twenty-eighth day of May, in the year of
our Lord One thousand eight hundred and forty.
THOMAS (L.S.) RICHARDSON.
Signed, sealed, and delivered (being
first duly stamped, by the said
Thomas Richardson, in the pre-
AND BE IT REMEMBERED, that on the Twenty-eighth day of May,
in the year of our Lord 1840, the aforesaid Thomas Richardson came before
our said Lady the Queen in Her Chancery, and acknowledged the Specifi-
cation aforesaid, and all and every thing therein contained and specified,
in form above written. And also the Specification aforesaid was stamped
according to the tenor of the Statute made for that purpose.
Inrolled the Ninth day of June, in the year of our Lord One thou-
sand eight hundred and forty.