AN IMPROVED METALLIC COMPOSITION AND PROCESS FOR COATING METALS AND PRESERVING THEM FROM OXIDATION
Year: 1878

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for the Invention of "AN IMPROVED
METALLIC COMPOSITION AND PROCESS FOR COATING METALS AND PRESERVING
THEM FROM OXIDATION." A communication from abroad by Albert Paul
Georges Daumesnil, of Paris, France.
Sealed the 25th June 1878, and dated the 16th April 1878.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 16th April 1878.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent. "AN IMPROVED METALLIC COMPOSITION AND PROCESS FOR COATING
METALS AND PRESERVING THEM FROM OXIDATION." [A communication from
abroad by Albert Paul Georges Daumesnil, of Paris, France.]
This Invention relates to a novel composition for coating metals or metallic sur-
faces, to prevent oxidation, and to the methods of applying the same.
To prepare the composition I take about 1 kilogramme of borate of lead, and grind
it in water in a mill (such as that employed in the porcelain manufacture for
grinding vitrifiable colors) until it is brought to a finely divided state, and is easily
held in suspension in water without the necessity of frequent stirring, and. when
this result is attained, it is placed in a vessel of sufficient capacity to contain about
two litres of water, and allowed to settle, after which the water used in the grinding
is drawn off. I then dissolve about 12 grammes of chloride of platinum crystals in
a litre of distilled water, and when completely dissolved, I add 25 centilitres of
ammonia in small quantities at a time, and well stir the whole with a glass spatula.
The aminonia precipitates the platinum in an extremely fine state of division in
the form of a brown powder, in the course of about three hours; after which, the
ammoniacal water is decanted off and replaced by pure water; it is then again stirred
with the spatula, and allowed to settle a second time for about three hours, after

page_text: which the water is decanted off, and the platinum obtained is mixed with the borate
of lead.
To ensure a thorough mixture of these two products, they are placed together in the
mill, and worked for at least half an hour, after which, 5 litres of water are added,
and the product is then ready for use. The piece of metal to be coated, whether of
steel, wrought or cast iron, copper, or other metal, after being cleaned or washed, is
to be dipped in the composition, and then placed in a muffle, and the heat raised
until the composition changes from a white to a black color, resembling that of dull
iron. The operation is now complete, and the piece of metal may then be removed
from the muffle and allowed to cool.
It will be understood that the Invention is not limited to the exact proportions,
manipulation, or mode of application above described.
The same results may be obtained by varying the proportions of the borate
of lead and of the platinum, and by substituting for the latter one of its congeners
or metals of the same group, such as palladium, osinium, or iridium, although
platinum is preferred on account of its lower price.
The composition may be applied with a brush to large surfaces of metal which
could not be conveniently dipped, the surfaces being afterwards subjected to the
action of a gas flame of a sufficiently. high temperature..
The action of the borate of lead is probably to attack the metal to be pro-
tected, and fuse the surface portion, and to aid by this fusion the union of the
platinum with the metal; during this transformation, the borax partially dis-
appears, leaving upon the surface of the article coated a mixture or alloy of lead,
platinum, and the metal to be protected, which forms an effectual preservative against
oxidation.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the
15th October 1878: 1
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent.Agent. " AN IMPROVED METALLIC COMPOSITION AND PROCESS FOR COATING
METALS AND PRESERVING THEM FROM OXIDATION.". A. communication from
abroad by Albert Paul Georges Daumesnil, of Paris, France.
This Invention relates to the manufacture of a novel composition to be used for
coating articles of metal, in order to prevent oxidation thereof, and to the process of
coating such articles with the said composition.
To manufacture the composition I take about 1 kilogramme (15,432 grains)
of borate of lead, and grind it in water in a mill (such as that employed in the
porcelain manufactory of Sèvres for grinding vitrifiable colors) until it is brought
to such a finely divided state as to be easily held in suspension in water without
the necessity of frequent stirring. When this result is attained, the water holding
the lead in suspension is placed in a vessel of sufficient capacity to contain about
two litres (3%, pints) and allowed to settle, after which the water used in the
grinding is decanted off. I then dissolve about 12 grammes (185 grains) of chloride
of platinum crystals in a litre (13% pints) of distilled water, and when completely
dissolved I add 25 centilitres [.44 (or nearly half) of a pint] of ammonia in small
quantities at a time, and well stir with a glass spatula.
The ammonia precipitates the platinum in an extremely fine state of division in
the form of a brown powder in the course of about three hours, after which I decant
off the ammoniacal water, and replace it by pure water; I then again stir with the
spatula, and allow it to settle a second time for about 3 hours, after which I
decant off the water, and mix the platinum obtained with the borate of lead.
To ensure a thorough mixture of these two products, I place them in the
mill and work them up together for at least half an hour, after which I add 5
litres (about 8% pints) of water. The product is then ready for use.
The process of coating metal surfaces with this improved composition is as follows:―
The piece of metal to be coated, whether of steel, wrought or cast iron, copper, or other
metal, after being brushed or washed to clean it, is dipped in the composition, and
then placed in a highly heated muffle, and the fire is urged until the composition
changes from a white to a black color resembling that of dull iron. The operation
is now complete, and the piece of metal may then be removed from the muffle
and allowed to cool.
It should be understood that the Invention is not limited to the exact pro-
portions, mode of manipulation, or application above described.
Similar results may be obtained by varying the proportions of the borate of
lead and of the platinum, and by substituting for the latter one of its congeners
or metals of the same group, such as palladium, osmium, or iridium, although
platinum is preferred on account of its lower price.
The composition may be applied with a brush to large articles of metal which
could not be conveniently dipped, the surfaces being afterwards subjected to the
action of a gas flame of a sufficiently high temperature.
The borate of lead probably attacks the metal to be protected and fuses the sur-
face portion thereof, and thus aids the union of the platinum with the metal;
during this transformation the borax partially disappears, leaving upon the
surface of the article coated a mixture or alloy of lead, platinum, and the metal
to be protected, which forms an effectual preservative against oxidation.
Having described the nature of the Invention, and the manner of performing the
same, I declare that what I claim as the Invention to be protected by the herein-

page_text: before in part recited Letters Patent is, the improved metallic composition, and the
process of coating metals therewith, substantially as and for the purpose herein
specified.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set my
hand and seal, this Fifteenth day of October, in the year of our Lord One
thousand eight hundred and seventy-eight.
A. M. CLARK. (L.S.)