IMPROVEMENTS IN COATING WROUGHT IRON
Year: 1857

page_text: LETTERS PATENT to the Revd James Burrow, of Ashford Parsonage,
Bakewell, for the Invention of "IMPROVEMENTS IN COATING WROUGHT
IRON."
Sealed the 3rd July 1857, and dated the 25th April 1857.
PROVISIONAL SPECIFICATION left by the said James Burrow at the
Office of the Commissioners of Patents, with his Petition, on the 25th
April 1857.
I, the Revd JAMES BURROW, of Ashford Parsonage, Bakewell, do hereby
declare the nature of the Invention for "IMPROVEMENTS IN COATING WROUGHT
IRON," to be as follows:-
To protect one or both surfaces of sheet iron and other forms of wrought
iron with a succession of coatings from solutions alone, whether by galvanism
or otherwise, of the oxides of zinc, lead, tin, and copper in all their varieties
and combination; and also in applying directly to sheet iron and other forms
of wrought iron a fused compound of borax, sodas, potashes, litharge, arsenic,
silica,orelse indirectly by first depositing thercon a clayey,calcareous,silicious,
or other earthy compound, and then further protecting the coated iron by
dipping it into a solution of the above-mentioned substances, and afterwards
fusing by heat until the desired glaze is obtained.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said James Burrow in the Great Seal Patent Office on the 13th
October 1857.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, the
Rey JAMES BURROW, of Ashford Parsonage, Bakewell, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fifth day of April, in the year of our Lord
Oue thousand eight hundred and fifty-seven, in the twentieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said James Burrow, Her special licence that I, the said James Burrow,
my executors, administrators, and assigns, or such others as I, the said James
Burrow, my executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at all times thereafter 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 "IMPROVEMENTS IN
COATING WROUGHT IRON," upon the condition (amongst others) that I, the
said James Burrow, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, should par-
ticularly describe and ascertain the nature of the said Invention, and in
what manner the same was to be performed, and cause the same to be filed
in the Great Seal Patent Office within six calendar months next and imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said James Burrow, do hereby declare the
nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof, that is to say:-
In carrying out the Improvements of my Invention, I construct a wooden
or other suitable trough of proper dimensions, and arrange down the sides or
ends, in parallel lines, about a quarter of an inch from line to line, other than
metallic slightly projecting pegs, which are to serve as stays or supports to
keep the sheets or plates to be coated in nearly a vertical position. I then
take thin straps or pieces of zinc and copper or of the coating metal and
copper or zinc, of sufficient length to admit of one or both ends projecting
above the ends or sides of the trough when bent into its shape and dimensions.
These straps may be arranged alternately in an horizontal position, or they
may be placed in one or more alternate layers, in such a way that the zinc or
coating metal is always uppermost; or when one end only projects above the

page_text: side or end of the trough I prefer that the zinc or coating metal should embrace
longitudinally the copper strap. I prefer that the straps should be about two
inches wide, and at the distance of about four inches from each other. I then
connect the projecting ends by means of any good conducting metallic medium,
or by placing the different metals in contact with each other, taking care that
they do not touch except at the terminations. The ends thus united I curve
downwards, and dip one termination of the series into a vessel containing an
acidulated solution; the other I immerse in a vessel containing hot water, or
heated sand bath, or an alkaline solution; it may be carbonate of potassa or
soda, or a weak solution of salammoniac. When this series of straps is in
its place in the trough I insulate it, by causing it to rest upon any of the well-
known non-conducting substances placed at the bottom of the trough. When
the series of straps or pieces is alternately zinc and copper, I prefer that the
acidulated mixture into which the union of their terminations dips should be
diluto sulphuric acid; when tin and copper, I use dilute muriatic acid, with
lead and copper dilute nitric acid. I then fill the trough with a weak solution
of the coating metal, about one ounce to every six gallons of water; having
stirred it well, I immerse the sheets or plates to be coated, placing them
between the parallel lines of pegs, and in contact with the zinc or coating
metal of the series of straps insulated at the bottom of the trough. These
sheets or plates I previously clean by dilute acid in the ordinary manner.
Sometimes I use the following arrangement of the electrolytic trough, pre
serving the slightly projecting pegs. I substitute for the series of metallic
straps bars of wood well carbonized, about four inches wide; of nearly the
same length as the bottom of the trough, and fastened together at the ends by
means of any good conducting metallic rods or bars, or it may be a bar of
wood well carbonized. These bars of wood I fix about three inches apart,
and place along the intermediate spaces straps or pieces of zinc, or of the
coating metal, causing them to rest upon the cross bars or rods that fasten the
ends of the longitudinal bars. When the sheets, &c. to be coated are in their
places, I prefer they should be in contact with the carbonized bars of wood,
and also with the metallic straps. With this arrangement I keep the metallic
solution very weak, about one ounce to ten gallons of water, at from about
180° to 200° Fahrenheit, and use a saline or alkaline exciting fluid. With
the chlorides of tin, zinc, or lead, I prefer a solution of chloride of sodium
somewhat stronger for zinc and lead, or it may be about 15 parts chloride of
sodium and 1 part bitartrate of potassa. When coating from a solution of
the sulphate of zinc, I prefer as the exciting agent sulphate of soda or potassa;
with the acetate of lead a weak solution of salammoniac; with the peroxido

page_text: of tin 12 parts chloride of sodium, 5 parts sulphate of potassa, and 1 part
bitartrate of potassa. Sometimes I dispense with all exciting agents, and
proceed by digesting the sheets, &c. to be coated in a weak solution of tin or
zinc at nearly boiling point. When using mercury as an agent in coating
from solutions of tin, zinc, or lead, I prefer the bichloride or nitrate of mercury,
and proceed either by dipping the cleansod sheets into a weak solution, say,
one ounce to about 25 gallons of water, and afterwards rinsing them in warm
water; or in the case of lead and zinc, I mix a small quantity of the mercurial
solution with the coating solutions of these metals thoroughly mix them by
stirring in the electrolytic trough arranged with the carbonized bars of wood,
iminerso the sheets, &c., and proceed at about 180° Fahrenheit. When
coating from the sulphate of copper, I prefer the arrangement with the series
of metallic straps, and render the solution just sensibly sour to the taste by
means of sulphuric acid. About every half hour I raise the sheets from their
places, bringing them in contact with a moveable roller or rollers spanning the
trough, and covered with buff leather or other soft material. I then invert
them and lower them into their places again in contact with the same
roller or rollers. When the desired coating has been obtained, I remove
the plates, wash them carefully in hot water, or in water slightly alkaline,
preferably with biborate of soda, and dry them very quickly before a coke
fire or in a hot oven. By the above process I coat sheets or plates of
cleaned iron from simple or compound solution, equalizing as nearly as
possible the compound solutions of tin, zinc, or lead.
When applying successive coatings from solutions of tin, zinc, lead, and
copper to sheets or plates of iron previously coated in the manner already
specified, I proceed either by means of the electrolytic trough and series of
metallic plates, as in the application of primary coatings, or by means of the
carbonized bars of wood. I take the coated sheets in the latter case, wash
them thoroughly with hot water, and either dip them or not into the mercurial
solution already mentioned; then when the successive coating is to bo zinc
upon a coating of tin, or lead, or copper, I prefer the sulphate of zinc, and
treat it as already described for coating the naked iron. When tin upon a
coating of zinc or lead, I prefer the chloride of tin, with the exciting fluid
partly saline and partly alkaline, already mentioned. Upon a coating of
copper I prefer using the saline solution only; when lead upon the zinc, tin,
or copper coating, I generally use the acetate or chloride of lead without any
exciting agency. In all these cases, except when the metallic solution is one
of tin or copper, I frequently mix a small quantity of the mercurial solution
with the coating solution and proceed at about 180° Fahrenheit; when the

page_text: successive coating is copper, I proceed to apply it by the same process as used
when coating the naked iron. For protecting the iron with a vitrified coating
I prefer the following proportions, although other compounds of the same
substances will have the desired effect; viz., 10 parts of carbonate of soda
and one part borax, or 50 parts silica, 6 parts litharge, and 2 parts borax; these
I reduce to a fine powder, thorougly mix and fuse in a vessel, similar to those
in use for vitrifying the materials of glass. Into this compound in a state
of liquifaction I dip the plates, sheets, &c., previously cleaned, stamped, or
shaped, and heated to a low red heat. In a few seconds I withdraw them,
and place them in a oven heated to about 300° Fahrenheit, and then allow
them to cool gradually. Before applying the vitrified coating to sheets, &c. of
iron, I sometimes protect the iron with a clayey, silicious, or other earthy com-
pound; for this purpose I profer two parts silica and five parts clay; these I
thoroughly.mix and powder,then reduce them to a smooth pulpy consistency.
Into this compound I dip the iron previously cleaned, stamped, or shaped;
in a few seconds I withdraw it, and place in a warm oven till sufficiently
dry to absorb the glazing mixture, which I prepare as follows:-I take 10
parts carbonate of soda, 5 parts borax, and 2 parts clay; or 10 partss ilica,
5 parts litharge, and 2 parts borax; this compound I thoroughly mix and
fuse, then cool, grind, sift, and reduce to a creamy consistency, into which
I immerse the iron previously coated as above; having withdrawn tho
sheets I gradually dry them till the glaze is set, then heat in a proper kil
or muffle till the desired devitrification takes place.
In witness whereof, I, the said James Burrow, have hereunto set my
hand and seal, this Eleventh day of September, in the year of our
Lord One thousand eight hundred and fifty-seven.
Witness,
CHARLES SPENCER,
Ashford.
JAMES BURROW. (L.S.)