IMPROVEMENTS IN THE MANUFACTURE OR PRODUCTION OF WHITE LEAD
Year: 1860

page_text: LETTERS PATENT to William Baker, of Sheffield, in the County of York,
Chemist, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE OR
PRODUCTION OF WHITE LEAD."
Sealed the 6th November 1860, and dated the 24th May 1860..
PROVISIONAL SPECIFICATION leit by the said William Baker at the
Office of the Commissioners of Patents, with his Petition, on the
24th May 1860.
I, WILLIAM BAKER, of Sheffield, in the County of York, Chemist, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN THE
MANUFACTURE OR PRODUCTION OF WHITE LEAD," to be as follows: -
This Invention relates to a more economical and efficient mode of producing
white lead than the processes hitherto adopted, and consists in substituting for
the acetic acid used in the ordinary Dutch process the salts of acetic acid,
which produce or set free that acid. The salts which I have found to answer
the purpose are acetate of lime, acetate of soda, and others of a like nature,
to which is added the chemical equivalent, or a slight excess thereof, of
sulphuric acid or hydrochloric acid, or of mixtures thereof, sufficient to take
up and combine with the base, and set free all the acetic acid. The salt
formed by this decomposition (which in the case of acetate of lime and sul-
Price 8d1

page_text: phuric acid is sulphate of lime) has the effect of retarding the evaporation of
the acetic acid. I have obtained good results from a mixture containing
about two per cent. of anhydrous acetic acid, and composed of 37 pounds of
commercial acetate of lime. containing 90 per cent. of the salt. 25 pounds of
sulphuric acid containing 78 per cent. of acid, and 120 gallons of water.
The strength of the mixture. however, may be varied at pleasure. Any
mixture would answer the purpose that leaves acetic acid free, which acid
would evaporate by the action of heat, whether generated by the fermentation
of tan, assisted or not by artificial heat. All the salts of acetic acid may be
decomposed by a stronger acid, such as sulphuric acid or hydrochloric acid,
or by bisulphates, as, for example, the bisulphate of potass or soda. The
retardation of the evaporation of the acetic acid at present employed may be
effected by simply adding thereto suitable proportions of salts, such as sulphate
of lime, sulphate of soda, or common salt.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Baker in the Great Seal Patent Office on the
23rd November 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
BAKER, of Sheffield, in the County of York, Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fourth day of May, in the year of our
Lord One thousand eight hundred and sixty, in the twenty-fourth year of
Her reign. did, for Herself. Her heirs and successors. give and grant unto
me, the said William Baker. Her special license that I, the said William
Baker, my executors, administrators, and assigns, or such others as I, the
said William Baker, my executors, administrators, or assigns, should at any
time agree with, and no others, from time to time and at all times there-
after 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 "IMPROVE-
MENTS IN THE MANUFACTURE OR PRODUCTION OF WHITE LEAD," upon the con-
dition (amongst others) that I, the said William Baker, by an instrument
in writing under my hand and seal, should particularly describe and ascer-
tain the nature of the said lavention, and in what manner the same was
to be performed, and cause the same to be filed in the Great Seal Patent

page_text: Office within six calendar months next and immediately after the date of
the said Letters Patent.
NOW KNOW YE, that 1. the said William Baker, 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, that is to say:--
My said Invention relates to a more economical and efficient mode of
producing white lead than is effected by those methods hitherto adopted, and
consists in substituting for acetic acid, as now used in the Dutch method for
the manufacture of white lead, salts of acetic acid, from which acetic acid
may be produced or liberated by the employment of either sulphuric acid or
hydrochloric acid, or mixtures thereof, or by the employment of acid sulphates
of the alkalies. The acetates which I have found to answer for this purpose
are the acetates of lime, acetates of soda, and the soluble acetates of the
alkalies, and the alkaline earths, or others of a like nature. To any of the
before-mentioned acetates I add a chemical equivalent of or a slight excess of
sulphuric acid, or of hydrochloric acid, or of mixtures thereof, or of the
bisulphates of soda or potass, in sufficient quantity to set free all the acetic
acid previously combined with the base. The salts or compound thus resulting
from the decomposition of the soluble acetates, which, in the case of acetate
of lime and sulphuric acid, is sulphate of lime, or when acetate of lime and
hydrochloric acid have been employed, then chloride of calcium has the effect
of retarding the evaporation of the liberated acetic acid. I have obtained
good results from a mixture containing about two per cent. of anhydrous
acetic acid. and composed of thirty-seven pounds of commercial acetate of
lime, containing ninety per cent. of the salt, twenty-five pounds of sulphuric
acid containing seventy-eight per cent. of acid, and one hundred and twenty
gallons of water: or, when hydrochloric acid is employed, then one hundred
and three pounds of hydrochloric acid. containing thirty per cent. of acid;
or, in the case of bisulphate of soda, a quantity representing ninety-one pounds
of crystallized bisulphate of soda. or an equivalent proportion of bisulphate of
potash. The strength of the mixture. however, may be varied at pleasure.
I do not confine myself to any of the before-mentioned mixtures, as any
mixture can be employed that produces acetic acid. which acetic acid so
liberated can be evaporated from its solution by the action of the heat
generated by the fermentation of tan in the stacks, either aided or not by the
introduction or application of artificial heat. In order to retard the evapo-
ration of acetic acid when employed, as at present, in the ordinary Dutch

page_text: method of the manufacture of white lead above mentioned, I add to the acetic
acid intended to be employed for that purpose certain salts, such as sulphate
of lime, sulphate of soda, or common salt, or any neutral salt.
In witness whereof, I, the said William Baker, have hereunto set my
hand and seal, this Twentieth day of November, One thousand eight
hundred and sixty.
WILLIAM BAKER. (L.S.)