IMPROVEMENTS IN EFFECTING THE PROTECTION OF IRON AND STEEL."
Year: 1878

page_text: LETTERS PATENT to George Bower and Anthony Spencer Bower, both of
St. Neots, in the County of Huntingdon, Engineers, for the Invention of
"IMPROVEMENTS IN EFFECTING THE PROTECTION OF IRON AND STEEL."
PROVISIONAL SPECIFICATION left by the said George Bower and Anthony
Spencer Bower at the Office of the Commissioners of Patents on the 1st April
1878.
GEORGE BOWER and ANTHONY SPENCER BOWER, both of St. Neots, in the
County of Huntingdon, Engineers. "IMPROVEMENTS IN EFFECTING THE PROTECTION
OF IRON AND STEEL."
This Invention relates to the protection of cast or wrought iron and of cast or
wrought steel surfaces from oxidation or corrosion by atmospheric or other
influences, and consists in the formation of a protective film or coating thereon of
oxide or of oxides of iron by the action of carbonic anhydride (CO2) at a suitable
temperature.
The carbonic anhydride (CO₂) may be produced by any convenient method, but,
preferably, by the combustion of carbonic oxide (CO), which carbonic oxide is
produced by any well-known and suitable means.
The chemical changes which take place, and on which the process is based, are
the following:-The carbonic anhydride, in presence of iron or steel at a suitably
elevated temperature, parts with one atom of oxygen, which it gives up to the said
iron or steel, forming an oxide or oxides of iron, and then passes off as carbonic
oxide (CO), which carbonic oxide can, if necessary, be re-converted by combustion
in a sufficient amount of air or of oxygen into carbonic anhydride (CO).
In carrying out this process, when applied to iron or steel objects, the surfaces of
which it is required to protect, are either subjected to the action of heat in a retort
or other suitable apparatus, which may be heated externally, and the carbonic
anhydride (CO) passed directly in amongst and over the articles under treatment,

page_text: or the said articles may be directly heated by the actual combustion of the carbonic
oxide in presence of a sufficient amount of air, the supply of which air may be
regulated by suitable valves or other contrivances; or the articles themselves may
be heated by employing a highly heated current of the carbonic anhydride in lieu
of or in conjunction with the carbonic anhydride at the ordinary temperature; or
the necessary carbonic oxide (which is to produce by its combustion the carbonic
anhydride) may be obtained directly from the fuel which is employed to effect the
heating of the chamber in which the articles under treatment are placed, the fuel
being burnt under such conditions that the products of combustion may be largely
composed of carbonic oxide, which carbonic oxide is led by suitable pipes or other
contrivances into the chamber over and among the articles therein, and be burnt
along with and in conjunction with a sufficient amount of air, so as to convert it
partly or entirely into carbonic anhydride.
It has been found to be advantageous in carrying out this process to have the
surfaces of the iron slightly coated with sesqui-oxide of iron or rust before sub-
mitting the same to the action of the carbonic anhyride, and this applies more
especially to articles of wrought iron.
The temperature which it is preferred to adopt in carrying out this process ranges
from a dull to a bright red heat.
The metallic objects upon which it is proposed to form a protective film or
surface of the desired oxide of iron may be composed either of cast malleable or
cast or wrought iron or of cast or wrought steel.
The metallic articles are to be submitted to the action of the before-mentioned
ngent in the manner before mentioned until the protective film or covering of the
desired thickness shall have been formed upon the exterior surface or portion of the
same; and when such requisite film or coating has been formed the metallic objects
may be allowed to cool, and are then ready for useful application in the arts.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said George Bower and Anthony Spencer Bower in the Great Seal Patent
Office on the 30th September 1878.
GEORGE BOWER and ANTHONY SPENCER BOWER, both of St. Neots, in the
County of Huntingdon, Engineers. "IMPROVEMENTS IN EFFECTING THE PROTECTION
OF IRON AND STEEL."
This Invention relates to the protection of cast or wrought iron and of cast or
wrought steel surfaces from oxidation or corrosion by atmospheric or other influences,
and consists in the formation of a protective film or coating thereon of oxide or
of oxides of iron by the action of carbonic anhydrides (CO₂) at a suitable tem-
perature.
The carbonic anhydride (CO) may be produced by any suitable method, but,
preferably, by the combustion of carbonic oxide (CO), which carbonic oxide is
produced by any well-known and suitable means.
The chemical changes which take place, and on which the process is based, aro
the following-The carbonic anhydride, in presence of iron or steel at a suitably
elevated temperature, parts with one atom of oxygen, which it gives up to the said
iron or steel, forming an oxide or oxides of iron, and then passes off as carbonic
oxide (CO), which corbonic oxide can, if necessary, be re-converted by combustion
in a sufficient amount of air or of oxygen into carbonic anhydride (CO).
In carrying out this process, when applied to iron or steel objects, the surfaces of
which it is required to protect, they are either subjected to the action of heat in a
retort or other suitable apparatus, which may be heated externally, and the carbonic
anhydride (CO2) passed directly in amongst and over the articles under treatment,
or the said articles may be directly heated, or partly heated, by the actual combustion
of the carbonic oxide in presence of a sufficient supply of air, the supply of which air
may be regulated by suitable valves or other contrivances; or the articles themselves
may be heated by employing a highly heated current of the carbonic anhydride in lieu
of or in conjunction with the carbonic anhydride at the ordinary temperature; or the
necessary carbonic oxide (which is to produce by its combustion the carbonic anhy-
dride) may be obtained directly from the fuel which is employed to effect the
heating of the chamber in which the articles under treatment are placed, the fuel
being burnt under such conditions that the products of combustion may be largely
composed of carbonic oxide, which carbonic oxide is led by suitable pipes or other
contrivances into the chamber over and among the articles contained therein, and
burnt along with or in conjunction with a sufficient amount of air, so as to couvert
it partly or entirely into carbonic anhydride.
It has been found to be advantageous, in carrying out this process, to have the
surfaces of the iron slightly coated with sesqui-oxide of iron or rust before sub-
nitting the same to the action of the carbonic anhydride or to the carbonic oxide
which is to produce the aforesaid carbonic anhydride; and this applies noro
especially to articles of wrought iron.
In order to obtain a coating of this sesqui-oxide of iron, and then convert or
reduce it to the magnetic or black oxide, the following modification of the before-
inentioned processes may be adopted when necessary:-The carbonic oxide is mixed
with a larger quantity of air (preferably superheated) than is requisite for con-
vertion into carbonic anhydride, and is passed into the chamber over and amongst
the articles. The free oxygen in the excess of air combines with the iron to form
a superficial coating of sesqui-oxide of iron; after this formation of sesqui-oxide has
continued for a sufficient length of time, which is determined by the temperature
employed, and the use for which the articles may be designed (half an hour will be
found in the majority of cases to be quite sufficient), carbonic oxide without
admixture with free oxygen or air is admitted in sufficient quantity to reduce this
sesqui-oxide, and by its consequent conversion into carbonic anhydride form in its

page_text: place a film of the requisite magnetic oxide. The time for which the carbonic oxide
alone is allowed to circulate in the chamber is dependent on the temperature and
amount of sesqui-oxide formed in the first operation, but, as a rule, three minutes'
exposure of the articles to carbonic oxide is found to be sufficient.
These operations may be continued as often as necessary, according to the thickness
of the protective film required.
The temperature which it is preferred to adopt in carrying out this process ranges
from a dull to a bright red heat.
The metallic objects upon which it is proposed to form a protective film or
surface of the desired oxide or oxides of iron may be composed either of cast
malleable or cast or wrought iron or of cast or wrought steel.
The metallic objects are to be submitted to the action of the before-mentioned
agent in the manner before mentioned until the protective film or covering of the
desired thickness shall have been formed upon the exterior surfaco or portion of
the same, and when such requisite film or coating has been formed the metallic
objects may be allowed to cool, and are then ready for useful application in the
arts.
Having now described and particularly ascertained the nature of our ŝaid
Invention, and the manner in which the same is or may be used or carried into
effect, we would observe in conclusion that what we consider to be novel and
original, and therefore claim as the Invention secured to us by the herein-before
in part recited Letters Patent is, effecting the preservation of objects or articles
consisting or composed either of cast iron, of malleable iron, or of wrought iron, or
of cast or of wrought steel, by submitting the same at an elevated temperature to
oxidizing processes in the manner substantially as herein-before described.
In witness whereof, we, the said George Bower and Anthony Spencer Bower,
have to this our Specification set our hands and seals, the Nineteenth day
of September, One thousand eight hundred and seventy-eight.