IMPROVEMENTS IN THE MANUFACTURE OF SALTPETRE AND WHITE LEAD
Year: 1866

page_text: LETTERS PATENT to Clarence Delafield, of Staten Island, in the County
of Richmond, State of New York, United States of America, for the
Invention of "IMPROVEMENTS IN THE MANUFACTURE OF SALTPETRE AND
WHITE LEAD."
Sealed the 25th May 1866, in pursuance of an Order of the Lord
Chancellor, and dated the 31st January 1866.
PROVISIONAL SPECIFICATION left by the said Clarence Delafield at
the Office of the Commissioners of Patents, with his Petition, on the
31st January 1866.
I, CLARENCE DELAFIELD, of Staten Island, in the County of Richmond,
State of New York, United States of America, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF
SALTPETRE AND WHITE LEAD," to be as follows:-
The nature of the said Invention consists chiefly in the production (by
the union of certain chemical constituents) of the carbonate of lead or
white lead and nitrate of potash or saltpetre simultaneously and in such
manner that the manufacture of either of these articles will yield the other
as a residue.
The manufacture of white lead according to my Invention will yield
saltpetre as a residue, and the manufacture of saltpetre will yield white
lead as a residue. Both articles being the result of one process and one

page_text: combination, a description of the mode of manufacturing one of the said
articles will be a description of the mode of manufacturing the other of
the said articles. In making white lead I take by weight fifty-four parts
of nitric acid and one hundred and four parts of lead and unite them in
about seven times their weight of water. I also take by weight eighty-
five parts of the carbonate of potash and unite it with about five times its
weight of water; these two mixtures being united from the carbonate of
lead or white lead and nitrate of potash or saltpetre. The carbonate of
soda may be substituted for the carbonate of potash and the proportions
of the ingredients may be slightly varied without essentially affecting the
result, but those mentioned are advantageously adopted.
SPECIFICATION filed in pursuance of the conditions of the Letters Patent,
and of an Order of the Lord Chancellor, by the said Clarence
Delafield in the Great Seal Patent Office on the 17th August 1866..
TO ALL TO WHOM THESE PRESENTS SHALL COME, I. CLARENCE
DELAFIELD, of Staten Island, in the County of Richmond, State of New
York, United States of America, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirty-first day of January, in the year of our
Lord One thousand eight hundred and sixty-six, in the twenty-ninth year
of Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said Clarence Delafield, Her special licence that I, the
said Clarence Delafield, my executors, administrators, and assigns, or
such others as I, the said Clarence Delafield, my executors, admi-
nistrators, and assigns, should at any time agree with, and no others,
from time to time and at all times thereafter during the term therein;
expressed, should and lawfully might make, use, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN THE MANU-
PACTURE OF SALTPETRE AND WHITE LEAD," upon the condition (amongst others)
that I, the said Clarence Delafield, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands and seals,
should particularly describe and ascertain the nature of the said Invention,
and in what manner the same was: to be performed, and cause the same to
be filed in the Great Seal Patent Office within six calendar months next
and immediately after the date of the said Letters Patent.

page_text: NOW KNOW YE, that I, the said Clarence Delafield, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and by.
the following statement :→
The white lead of commerce, as manufactured after the old or what is-
known as the Dutch process, consists of the carbonate of lead united with
the hydrated oxide of lead in about the proportion of two chemical
equivalents of the carbonate of lead to one equivalent of the hydrated
oxide of lead. The mechanical means and the chemical agencies employed
in the manufacture of the white lead of commerce after the old process are-
familar to every one skilled in the arts to which this Invention appertains;:
but the formation and chemical union of the carbonate of lead and the
hydrated oxide of lead which takes place in and forms a part of that
process, is not so well understood. It is believed, however, that the
acetic acid driven off from the vinegar by the heat induced by the fer-
mentation of the tan bark or horse manure against metallic lead surrounded
by an atmosphere of water vapor and carbonic acid gas forms oxide of
lead, and these three chemical equivalents of the oxide of lead in process
of formation take from this atmosphere one equivalent of water and two
equivalents of carbonic acid gas, yielding as the result of the chemical
action carbonate of lead united with the hydrated oxide of lead in about
the proportion above stated. This I understand to be the theory of the
formation of the white lead of commerce by the old process; whether this
theory of the chemical action be correct or not, I do not know, it is not
proved, but I take it to be the recieved theory among chemists. However
this may be, the fact remains that the white lead of commerce consists of
about the chemical constituents above stated, instead of the pure carbonate-
of lead. Now I have discovered that the white lead of commerce instead.
of being made by the slow Dutch process can be made very much quicker
and equally as good or better by making, manipulating, and uniting a solu-
tion of the nitrate of lead and a solution of the carbonate of potash in such
a manner as to yield a precipitate of the carbonate of lead united with the
hydrated oxide of lead which is the white lead of commerce. The manner
of making, manipulating, and uniting these solutions so as to obtain the
above-mentioned result I will now proceed to describe in detail.
I first take from one hundred and twelve to one hundred and twenty-
four parts of the nitric acid of commerce of about 36° Baumé; to this I
add one hundred and twelve parts of the oxide of lead and sufficient water'
to make a saturated solution of the nitrate of lead; and in order to convert

page_text: quickly the mixture of the nitric acid and the oxide of lead and water into
a solution of the nitrate of lead I make the mixture hot. I then take
about seventy parts of the purified carbonate of potash and dissolve it in
its weight of water, forming a solution of the carbonate of potash and
water, which I also make hot. In making the solution of the nitrate of
lead I use hot water and raise the temperature of the mixture to about
200° of Fahrenheit. And in making the solution of the carbonate of
potash I use boiling water, the temperature of which is lowered by mixing.
in the potash, and which I afterwards raise to about 200° of Fahrenheit.
Having thus made and heated these solutions I throw the hot solution of
the carbonate of potash into the hot solution of the nitrate of lead, by which
I at once precipitate the carbonate of lead and leave the nitrate of potash
in solution, while at the same time I prevent the precipitate carbonate of
lead from crystallizing, and get also a small proportion of the hydrated
oxide of lead in combination with the carbonate of lead. The result of
this process is an approximation of what is sought for, but it does not yield
so large a proportion of the hydrated oxide of lead in chemical com-
bination with the carbonate of lead as is contained in the white lead of
commerce. Now in throwing the hot solution of the carbonate of potash
into the hot solution of the nitrate of lead, there seems to be a complete
chemical union between the carbonate of lead and the hydrated oxide of
lead until about two-thirds of the alkaline solution has been added to the
nitrate of lead solution, when the formation of the hydrated oxide of lead
seems to stop, so that in adding the other third of the alkaline solution
pure carbonate of lead is formed. It is therefore necessary to change the
molecular formation of this remaining carbonate of lead by adding the neces-
sary proportion of hydrated oxide of lead, for which
I introduce
purpose
into the tank containing the united solutions a jet of hot steam through
metallic or flexible pipes, and continue the application until the whole
solution or mass is thoroughly pervaded or heated by the steam, when it
will be found that hydrate oxide of lead has been formed and united to the
carbonate of lead in about the proportion above stated. The apparatus or
means of applying the steam to the solution or precipitated salts may be
varied to suit the circumstances or taste of the manufacturer, but it should
be applied through pipes or orifices and with sufficient force to diffuse it
well through the solution or mass in case it be applied to the salt after
precipitation. In what way the jet of steam operates upon the solution,
salt, or mass is difficult to affirm. The beneficial effect may be owing to
the increase of temperature resulting from the introduction of the steam,

page_text: or it may be owing to the electricity generated by the passage of the
steam through the pipes, the electricity enlarging and accelerating the.
chemical combination that takes place between the elements present be
they what they may.. I incline to the belief, however, that the same
result will be obtained by raising the temperature of the combined
solutions by the application of heat thereto, whether in the form of steam
or in any other suitable form. I do not, therefore, mean to confine my
claim to the application of heat in the form of steam, but whatever may be
the true theory in regard to the chemical action, the fact is, that by the
introduction of the steam as above stated I get the result sought for, that
is the white lead of commerce, quicker, whiter, and purer than can be
obtained by the oid or Dutch process. In stating my improvements in
the manufacture of white lead I have described my improvement in the
manufacture of saltpetre also, for in the use of this process after the salts
of lead have been precipitated I get as a residue a hot solution of the
nitrate of potash which may be drawn off, evaporated, and rapidly
crystallized into a very fine saltpetre of commerce.
im-
Having now ascertained and described the nature and extent of my
provement in the manufacture of the white lead and saltpetre of commerce,
I claim as new and desire to secure by Letters Patent,-
First, uniting and combining a solution of the nitrate of lead (or its
equivalent for this purpose) made substantially as described with a solution
of the carbonate of potash (or its equivalent for this purpose) made
substantially as described for the purpose of producing the white lead of
commerce.
Second, uniting and combining a hot solution of the carbonate of potash
(or its equivalent for this purpose) with a hot solution of the nitrate of
lead (or its equivalent for this purpose) for the purpose of producing the
white lead of commerce.
Third, the application of a jet of steam to a solution of the nitrate of
lead or to a solution of the carbonate of potash (or their equivalents for this
purpose) or to the united or combined solutions of the nitrate of lead and
carbonate of potash (or its equivalent for this purpose) for the purpose of
aiding in the production of the white lead of commerce, substantially as
set forth.
Fourth, the production of saltpetre or nitrate of potash, as the residue
of white lead manufactured after the process, substantially as described.
Fifth, raising the temperature of the solutions of the nitrate of lead and
the carbonate of potash after their union or combination, either by the use

page_text: of hot steam or by the application of other heat to aid in the production of
the white lead of commerce, substantially as described.
In witness whereof, I, the said Clarence Delafield, have hereunto set
my hand and seal, the Third day of July, in the year of our Lord
One thousand eight hundred and sixty-six.
Witnesses,
AMOS BROADNOX.
PETER D. KENNEY..
CLARENCE DALAFIELD. (L.S.)