AN IMPROVED PROCESS FOR MAKING A BLACK PIGMENT AND POLISHING MATERIAL
Year: 1884

page_text: I, ANDREW FRENCH, of 29 Washington Terrace, North Shields, in the County of
Northumberland Metallurgist, do hereby declare the nature of my said Invention
for "AN IMPROVED PROCESS FOR MAKING A BLACK PIGMENT AND POLISHING
MATERIAL" to be as follows:-
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My said Invention has for its object the making of a black pigment which
whilst costing little and being easily manufactured possesses good qualities, and is
innocuous. The material forming the pigment can also be advantageously used
for polishing metal and other surfaces like plumbago or what is commonly known
as black lead."
"
cwt.
In carrying out my Invention I take what is known as "lead fume" and is a
sublimate formed in furnaces in which lead ores are smelted, and is deposited in
the flues and condensers connected with such furnaces; and I mix this sublimate
in a solution of an alkaline sulphide, using by preference the sulphide of sodium.
For every ton of the sublimate a solution should be used containing about 3
(anhydrous) sulphide of sodium, this proportion being suitable for dark gray lead
fume or "blue fume." When, from the nature of the lead ores, the calcination of
them, or the conditions under which they are smelted, the resulting sublimate is of
a whiter color, a larger proportion of the sulphide of sodium will be required. The
black pigment, which is formed immediately on mixing the sublimate in the
solution, is separated by filtration, and is washed and dried and afterwards gently
crushed. It is then ready for use, for being made into paint, or for being packed
for the market. The solution filtered from the black pigment contains sulphite
and hyposulphite which may be recovered by well known means and be utilised.
The black pigment obtained in the manner described is a peculiar sulphide.of
lead of an intensely black color and of great body and covering power. It mixes
well with oil to form paint, and being insoluble in lactic and other organic acids
cannot injuriously affect those working with it.
Dated this Eighth dow of Mon 1904.
EDMUND HUNT,
Applicant's Agent.

page_text: I, ANDREW FRENCH, of 29 Washington Terrace, North Shields, in the County of
Northumberland, Metallurgist, do hereby declare the nature of my said Invention
for "AN IMPROVED PROCESS FOR MAKING A BLACK PIGMENT AND POLISHING
MATERIAL" 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 has for its object the making of a black pigment which whilst
costing little and being easily manufactured possesses good qualities and is
innocuous. The material forming the pigment, can also be advantageously used
for polishing metal and other surfaces like plumbago or what is commonly known
as "black lead."
In carrying out my Invention I take what is known as "lead fume" and is a
sublimate formed in furnaces in which lead ores are smelted, and is deposited in
the flues and condensers connected with such furnaces. I mix this sublimate in a
solution of an alkaline sulphide, using by preference the ordinary sulphide of
sodium made by furnacing in the usual way practised by alkali makers a mixture
of sulphate of soda and small coal. For every ton of the sublimate a solution
should be used containing 3 cwt. (anhydrous) sulphide of sodium, (that is the
mixed mono and poly-sulphides of sodium formed when sulphate of soda and coal
are furnaced as herein before mentioned) this proportion being suitable for dark
grey lead fume or "blue fume." When from the nature of the lead ores, the
calcination of them, or the conditions under which they are smelted, the resulting
sublimate is of a whiter color, a larger proportion of the sulphide of sodium will
be required. The black pigment, which is formed immediately on mixing the
sublimate in the solution is separated by filtration, and is washed, pressed, and
dried and afterwards gently crushed. It is then ready for use, for being made
into paint, or for being packed as dry pigment or polishing material for the market.
The solution filtered from the pigment contains sulphite and hyposulphite of the
alkali employed, which may be recovered by well known means and utilised.
In the mixing operation I prefer to gradually add the sublimate to the sulphide
solution until the latter becomes exhausted, stirring all the time, in which way a
more uniform and perfect black is obtained. The sulphide solution is known to be
exhausted when it no longer strikes a black color on a drop of it being let fall
upon a spot of lead fume on white paper.
The black pigment obtained in the manner described is a peculiar sulphide of
lead of an intensely, black color, and of great body and covering power. It mixes
well with oil to form paint, and being insoluble in lactic and other organic acids
cannot injuriously affect those working with it.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed, I declare that what
I claim is
Making a black pigment and polishing material by mixing sublimate of lead or
lead fume with an alkaline sulphide as hereinbefore described.
Dated this Fifteenth day of September 1884.
EDMUND HUNT
Applicant's Agent.