AN IMPROVED METHOD OF PREVENTING THE OXIDATION OF METALS
Year: 1838

page_text: DE FONTAINEMOREAU'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PIERRE
ARMAND le Comte DE FONTAINEMOREAU, of Charles Street, City Road, in the
County of Middlesex, Gentleman, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Iler
Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Fifth day of May, One thousand eight hundred and thirty-
eight, did, for Herself, Her heirs and successors, give and grant unto me, the
said Pierre Armand le Comte de Fontainemoreau, Her especial license, full
power, sole privilege and authority, that I, the said Pierre Armand le Comte
de Fontainemoreau, my exors, admors, and assigns, or such others as I, the
said Pierre Armand le Comte de Fontainemoreau, my exors, admors, or
assigns, should at any time agree with, and no others, from time to time and
at all times during the term of years therein mentioned, should and lawfully
might make, use, exercise, and vend; within England, Wales, and the Town of
Berwick-upon-Tweed, my Invention of "AN IMPROVED METHOD OF PREVENTING
THE OXIDATION OF METALS," being a communication from a foreigner-residing
abroad; in which said Letters Patent is contained a proviso, obliging me,
the said Pierre Armand le Comte de Fontainemoreau, by an instrument in
writing under my hand and seal, particularly to describe and ascertain the
nature of the said Invention, and in what manner the same is to be per-
formed, and to cause the same to be inrolled in Her 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.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Pierre Armand le Comte de Fontainemoreau, do hereby declare that the
nature of the said Invention consists in certain improved processes of coating,

page_text: covering, or enveloping metals liable to oxidation with zinc, or some alloy of
zinc, or with a paint, paste, or powder, of which zinc or an alloy of zinc is
a principal ingredient, and I declare that the manner in which the same is to
be performed is fully shewn in the following particular description of the said
improved processes (that is to say) :-
Whereas a Patent, of date the Twenty-ninth of April, One thousand eight
hundred and thirty-seven, was granted to Henry William Craufurd, then of
John Street, Berkeley Square, Commander in the Navy, for an Improvement
in Coating or Covering Iron and Copper for the Prevention of Oxidation,
which improvements were by the Specification therein-after inrolled by the
said Henry William Craufurd declared to consist in coating iron and copper
with zinc, either in a state of fusion or in a solid state reduced into powder
and applied as a powder and as a paint, which coating of zinc was in some
cases to be covered with a second coating of pure tin: and whereas the
methods of effecting the said objects specified by the said Henry William
Craufurd are in several respects defective and erroneous, and zinc may be
employed in other forms and states than those pointed out by him, I declare
that the object of the said Invention is to remedy the defects and errors in
the said methods, and by various new modes to render zinc more universally
applicable to the protection of metals from oxidation; and,
First, as to the preparation of metals to receive the zinc coating or
covering, I declare that I follow severally the same process as that described
by the said Henry William Craufurd, namely, by immersing them in an
acidulated bath, and then scouring them in order to remove any oxide or
extraneous matters which may be adhering to the surfaces thereof. When it
is not convenient to apply the coating immediately after the articles are taken
out of the bath I deposit them in the meanwhile in lime water or some
similar alkaline solution. In melting the zinc into which the articles to be
coated are to be plunged, the Specification of the said Henry William
Craufurd directs that the zinc shall be covered with sal ammoniac, but
instead thereof I use with success rosin and borate of soda and any black or
white flux capable of preserving zinc from oxidation. The zinc, according to
the methods specified by the said Henry William Craufurd, is applied only in
a state of fusion or in a solid state reduced to powder and mixed up into a
paint, but I apply it more frequently in a state of dry powder, which I
prepare as follows:-The zinc is put into a reverberatory furnace, every
opening for the admission of the atmospheric air carefully closed, and the
temperature of the melted zinc raised to a degree approaching red heat.
The door is then opened and the zinc skimmed, after which one-tenth of its

page_text: weight of wrought (not cast) iron filings moistened with muriatic acid (to
which some sal ammoniac may be added) is thrown into the fused metal,
which must be stirred all the while; after the introduction of the filings the
surface of the metal must be covered over with fine charcoal powder, and
the temperature carried to about the cherry-red heat, at which temperature
the metal must be maintained for one hour, stirring it occasionally with an
iron poker. The melted metal is then conveyed into a brick or cast-iron
trough covered over with a lid of cast iron to exclude all contact with the
atmosphere; the metal is then stirred by means of an iron rod passing
through a hole in the cast-iron door until by cooling it becomes so solid that
it can be stirred no longer; when quite cool it is ground into powder, and
the more friable it is the better the operation has succeeded. The powder so
obtained will preserve from oxidation copper and iron, polished and filed steel,
such as clockwork, articles of hardware, ironmongery, &c., by merely covering
the articles with the powder, and this even though they should be exposed to
wet or damp. The zinc may be also applied through the medium.of a paint or
paste, in manner which I shall next proceed to describe:-The powder of zinc
is mixed with any of the unctuous substances generally used in paints and
varnishes. The substances which have been found to answer best are those
which were conductors of galvanic fluid, and hence this been has been com-
monly called galvanic paint. Very good paint is to be made with oil distilled
from the refuse tar of the gas manufactories, adding one-third of spirit of
turpentine; oil varnish may also be used, but it is very expensive; linseed
oil may be employed as it is in common paint, but is not quite so favorable
to the galvanic effect of zinc; lead or ceruse may be added to the paint
to give it some consistence. The proportions of the materials of the paint
depend on the substances with which the zinc powder is mixed, and on the
uses to which the paint is to be applied. With the same powder a paste may
be made; by rubbing copper, steel, and filed or polished iron with the same
they will be effectually protected. This paste is made with melted wax, into
which is put ten times its weight of powder of zinc and about one-fiftieth of
tallow or oil.
For protecting small polished metal articles I employ a zinc paper or
wrapper, manufactured by mixing powder of zinc ground very fine with
the pulp of the paper while making, or by powdering common paper pre-
viously covered with some glutinous substance, such as gum or flour paste,
taking care always to exclude the use of animal glue, which has a tendency
to cause the iron to rust. After copper and iron have been zinced according
to any of the modes herein-before described they may be still further protected

page_text: by scraping them with wet sandstone, and then moistening them with a
rag dipped in a solution of sal ammoniac, by which means a muriate of
zinc is formed equal in point of adherence to hard varnish. I find this
addition particularly useful in the case of fire-arms, filed and polished steel
articles, &c. For these articles zincing according to the methods described
The
in the Specification of Henry William Craufurd is not sufficient.
zinc employed must be very pure, and if melted in earthenware crucibles
these crucibles must, where the articles are large, be placed in other
crucibles of iron or cast iron. The empty space between the earthen and
cast-iron crucibles must be filled up with fine sand or lead; the melted
zinc is then covered over with sal ammoniac, as in the other methods; but
to prevent the sal ammoniac from staining the articles by adhering to them
when they are drawn from the bath, some earthy substances, such as
gravel, sand, lime, or chalk, in pieces or powder, are mixed with sal
ammoniac. After the pieces are well covered over with the ziucing they
are polished. First, all unevenness in the zinc coating is made to
disappear, which is effected by means of files or scrapers; afterwards
pumice stone, sand stone, or emery paper is used, and then the polishing is
terminated as in the case of any other metal. It is important not to use hard
bodies; to make the coating smooth and give the polish, cork, leather, rags,
or other similar things should be employed; without this precaution the zinc
might be rubbed off in some places. It is to be observed that to take the
polish well the articles should not be previously polished. When cannon balls
or other large articles are required to be protected from oxidation, they should
be heated in a reverberatory furnace, or otherwise, previous to their being
zinced. The screws and other parts of iron that do not require to be pro-
tected, may be covered with a thin coating of clay, and where there are holes
these holes may be stopped up with wood. If it is desired that the protected
articles should possess a peculiar grey color different from that of zinc, they
must be plunged in red hot zine; or, having been plunged in zinc less hot,
they must be heated red hot in a reverberatory furnace. A great disadvantage
has been found to result from the contact of the fuzed zinc with the iron or
cast-iron crucibles, in fact, an alloy of zinc and of iron is soon formed, by
which the iron is so changed as to be nearly worthless, while in a few days
the crucible is perforated and completely spoiled. To obviate this incon-
venience a large quantity of lead is melted in the iron or cast-iron crucible,
and only a small quantity of zinc added. The zinc being lighter than lead,
and not combining sensibly with that metal, always remains at the surface, and
covers alone the iron plunged in the crucible, as if it contained nothing but

page_text: zinc. As the layer of zinc covering the lead might yet spoil the crucible, an
iron hoop is placed in the interior of the crucible so as to reach the lead, and
to prevent the zinc penetrating between the hoop and the crucible, the space
between is stopped up with clay. By these means, the zinc, instead of spoil-
ing the crucible, only spoils the hoop, which can easily be replaced by another.
Instead of an iron hoop an earthen one would perhaps be preferable, which,
like the iron one, would descend lower than the level of the lead; but it must
be observed that the hoop should be fixed before any zinc is put into the
crucible, to prevent any zinc getting between it and the hoop. The best
method of heating the crucibles consists in surrounding them with either coke
or charcoal. To protect nails and other similar articles they are first placed
in a wire basket, or in a vessel of any form perforated with a great many
holes; this basket or vessel is then plunged in melted zinc, and the metal bath
covered with a layer of sal ammoniac. The basket being drawn out of the
bath is carefully shaken, so that any excess of the zinc adhering may fall off,
and then it is thrown into water or some other fluid; provided always that the
fluid is such that it will not attack the sal ammoniac. It is very important to
seize the proper moment for throwing the articles into the water, but the tact
in this respect is only to be acquired by practice. A perforated cylinder, or
any machine of a similar kind revolving on its axis, may be used for finishing
the nails and other like articles. As soon as taken out of the bath they
should be thrown into the machine then revolving on its axis, and this machine
should be heated to a degree sufficient to prevent any superfluous zinc stopping
up the holes. In the methods of protection herein-before specified, zinc and
the alloys of zinc are applied in the state only of powders, paints, or pastes,
but I now proceed to describe how solid plates of zinc may be combined with
other metals for their protection from oxidation; or in other words how copper,
iron, and other metals may be plated therewith. The iron or copper, or other
metal being previously cleaned according to the means described in the said
Henry William Crawfurd's Specification, the article is covered with thin sheet
zinc, well powdered with sal ammoniac, and the two sheets of metal are then
passed through heated rollers, from which they are received into water in a
state of perfect combination; I declare also, that I occasionally employ for
the preservation of metals alloys composed of zinc and tin, or lead, or bismuth,
or quicksilver, by melting any of these metals in a crucible with zinc, and
putting the article which is to be operated upon in such mixture. When the
melting takes place a small quantity of sal ammoniac is thrown in, and the
mixture left to evaporate at a slow fire, after which the article operated upon
is before getting cold thrown into cold water. It is to be observed, that all

page_text: the articles to be so prepared must have been previously cleaned of every
impurity according to the method aforesaid.
And having now particularly described the said improved proccesses of
coating or covering metals to protect them from oxidation, I declare that I do
not claim as the Invention communicated to me the powder made from zinc,
nor the paint or paste made with it, as they are already spoken of in Craw-
furd's Specification; but I claim the improved processes before described of
making powder of zinc, and of applying the same in a dry state as well as in
the state of a paint or paste for the protection of metals from oxidation.
I claim also the process herein-before described of alloying or combining
zinc with other metals and substances for the said purposes, and likewise the
process before described of covering plates of metal with sheets of zinc by
means of heated rollers. And such the said Invention being to the best of
my knowledge and belief entirely new, and never before used within that part
of Her said Majesty's United Kingdom of Great Britain and Ireland called
England, Her said Dominion of Wales or Town of Berwick-upon-Tweed, or
in any of Her Colonies or Plantations abroad, I do hereby declare this to
be my Specification of the same, and that I do verily believe that this my said
Specification doth comply in all respects fully and without reserve or disguise
with the proviso in the said herein-before in part recited Letters Patent
contained; wherefore I hereby claim to maintain exclusive right and privilege
to the said Invention.
In witness whereof, I, the said Pierre Armand le Comte de Fontaine-
moreau, have hereunto set my hand and seal, this Fifth day of
November, One thousand eight hundred and thirty-eight.
LO DE FON (L.s.) TAINEMOREAU.
AND BE IT REMEMBERED, that on the Fifth day of November, in the
year of our Lord 1888, the aforesaid Pierre Armand le Comte de Fontaine-
moreau came before our said Lady the Queen in Her Chancery, and acknow-
ledged the Specification aforesaid, and all and every thing therein contained