IMPROVEMENTS IN PREPARING METALS FOR THE PREVENTION OF OXYDATION
Year: 1839

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
DOWLING, of Chapel Place, Oxford Street, in the County of Middlesex,
Gentleman, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Twenty-fourth day of January, in the second year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Thomas Dowling, Her especial licence, full power, sole privilege and authority,
that I, the said Thomas Dowling, my exors, adññors, and assigns, or such others
as I, the said Thomas Dowling, my exors, adññiors, 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 expressed, should and lawfully might make, use, exercise,
and vend, within England, Wales, and the Town of Berwick-upon-Tweed,
my Invention of "IMPROVEMENTS IN PREPARING METALS FOR THE PREVENTION OF
OXYDATION;" in which said Letters Patent is contained a proviso, that I, the
said Thomas Dowling, shall cause a particular description of the nature of my
said Invention, and in what manner the same is to be performed, to be
inrolled in Her said 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
Thomas Dowling, do hereby declare the nature of the said Invention consists

page_text: certain improvements of preparing metals for prevention of oxydation
And I declare that the manner in which I perform the same is fully shewn in
the following particular description of the said improvements in preparing the
metals (that is to say) :-
The pieces of metals intended to be prepared are to be first dry rough
ground upon coarse grinding stone, such as are commonly used for grinding
the coarsest hardwares. I say dry rough ground, because it is usual to grind
wet, that is, that in general the stones are made to revolve in a trough containing
water, or a small current of water is made to flow upon the stones whilst they
are running, whereas it is essential to my purpose that the pieces of metal be
ground with stones quite dry. The grinding will be completed when every
part of the surface of the metal has received a rough polish. The pieces,
when so ground or rough polished, are to be put immediately into what I call
a conservative bath, in which they are to remain not less than forty-eight
hours, after which time they may be taken out as they are wanted for con-
tinuing the processes of preparation. This, which I call the conservative bath,
is composed as follows, (that is to say,) into a suitable vessel I put one hundred
and twenty gallons of soft or rain water, to which I add one hundred and
twenty pounds of soda of commerce, thirty pounds of chalk or very good quick-
lime, and one gallon of pure olive oil; these ingredients are to be well stirred
up together, and in twenty-four hours after the bath will be fit for use, and
the pieces of ground or rough polished metal may then be put into it, but
great care must be had not to let them touch each other, and the liquid ought
to be kept as quiet as possible, as the liquid wastes by evaporation and use;
the vessel may be refilled by adding fresh liquid, observing carefully to use the
same proportion of ingredients as above given. When the pieces of metal are
taken out of this bath to undergo the next process of preparing, they are to
be put in the sun or in any warm place to dry quickly, but on no account are
they to be rubbed for the purpose of drying them.
The next process to which the metals are to be submitted in the order of
preparation is what I call operating, which process, as well as the machines
and tools with which it is achieved, I will now fully describe, (that is to say,)
this process of operating is the rubbing of the ground or rough polished
surfaces of the metals, either in a hot or cold state, with zinc, until they have
acquired a soft smooth face and zincky appearance, which is palpable to the
touch as well as to the eye. The better to effect this in a superior manner as
well as with economy, I make use of certain machines and tools of various
forms and sizes. The principal machines which I make use of for this purpose
are what I call operating zinc wheels. These wheels may be made of any

page_text: diameter and breadth, and they may be constructed of any material suitable.
They are to be fixed upon axles in the ordinary manner, and made to revolve
in a framing or framings sufficiently strong to resist the required speeds.
The whole or parts of the circumference of these wheels is or are to be covered
with zinc, and I do not confine myself to any particular mode of placing and
fixing the said zinc upon the said whole or parts of the circumference of the
wheels. Wheels, pulleys, or cylinders of solid zinc will answer the purpose
very well; but that which I find to be the best and cheapest is to cast a ring
or rim of zinc two or three inches thick upon and about the circumference of
a cast-iron pulley wheel or cylinder, having one or more grooves in its or their
circumference or circumferences. Now, when this ring or rim of zinc is cast
upon the said wheel, cylinder, or pulley, a part of the melted zinc will run into
the groove or grooves of the said wheel, cylinder, or pulley, which will hinder
the said ring or rim of zinc from becoming loose, which otherwise it is liable:
to when running at very high speeds and heavily pressed upon by the pieces
of metal in the act of operating. These wheels require to be perfectly cylin-
drical, which is easily accomplished by turning them true upon the bearings in
which they are to operate. The speed of these operating zinc wheels varies
according to the nature of the work, but I prefer to employ three wheels in
succession. The first wheel makes or revolves at the rate of one thousand
two hundred feet at the circumference per minute, the second wheel revolves
two thousand feet per minute, and the third wheel revolves four thousand.
feet per minute, but I do not confine myself to these particular speeds
alone.
The workmen are protected by strong wooden guards from accident, in case-
the wheel breaks whilst working at these high speeds. The manner of opera-
ting is very simple, and is the same as that which is practised by grinders and
polishers of iron and steel goods (that is to say) by holding the pieces under
operation upon the wheels and pressing thereon more or less, as may be
practicable or necessary. The pieces of metal to be operated upon are first
submitted to the slowest wheel, and to be finished with the wheel of quickest
speed.
In preparing pieces of copper or iron which have curvelinear and angular
forms, and which cannot be submitted to the circular action of the grinding
5 stones and the operating zinc wheels, the grinding or rough polishing is to be
replaced by rasp or very rough filing, and the process of operating is to be
done by hand with what I call zinckers, which are tools made of zinc, and which
tools are of almost every form and size, to suit the curves and angles of the
pieces to be operated upon. The operation of zincing with these zinckers is

page_text: simply that of rubbing as hard as possible upon the surface of the metals
which have been rasped or rough filed with the tool or zincker in the manner of
filing, until the said surfaces have acquired the appearances before named. In
operating upon very large plates of metal, such as boiler plates, plates for
large vats or brewing coppers, &c., &c., I use what I call lumps, which are
heavy pieces of zinc in form of cube or otherwise, and the process of opera-
ting with the lumps is by moving them backwards and forwards upon the
surface of the said plates by an alternate movement. During the process of
operating, whether with the operating zinc wheels, the zinckers, or the lumps,
it will be advantageous from time to time to throw on the surface of the
metal under operation a little finely powdered salammoniac. When the pieces
of metal have got a sufficient dose of zinc in the process of operating, they
are to be taken to what I call the galvanic vapour furnace, for the purpose
of undergoing what I call the galvanic process; the construction of the said
galvanic vapour furnace, as well as the manner of working it in order to
complete the galvanic process, I will now describe, reference being had to the
Drawings hereunto annexed, and to the figures and letters marked thereon,
(that is to say,) in the Drawings A, B, C, D, are shown, first, a sectional
plan; second, two vertical sections; third, an end view of said galvanic
vapour furnace. This said furnace is composed of a heating furnace, with
grate and bars F; vapour galvanic furnace V; with crucible J; condensing
flue H. The figures of reference are as follows:-No. 1 is a crucible, made
of refractory or fire clay in the manner and of similar materials as the cru-
cibles used by glass blowers; No. 2 is the heating furnace, with grate bars
furnace; No. 3 is the ash-hole; No. 4 is the galvanic vapour furnace; No. 5
is the condensing flue; 6 is the chimney; 7 is a small flue with a damper,
which communicates between the galvanic vapour furnace V and the con-
densing flue H; 8 is another small flue with a damper, which comma:
nicates between the heating furnace and the condensing flue. The flue
No. 8 is to be used only when the fire in the furnace has been newly
lighted; afterwards when the galvanic vapour furnace has acquired a heat
sufficient to melt lead, then the damper in the flue No. 8 is to be closed,
and the damper in the flue No. 7 is to be opened. No. 9 is a flue and
damper communicating with the chimney, which is kept open or shut as cir-
cumstances may require, and which can be judged only by the person who has
acquired some experience in directing this process. In the furnace F an arch
is built over the whole length and width of the grate bars, and the heat is
communicated first to the bottom and sides of the crucible, and afterwards
passes into the vapour furnace by the small flue No. 10; without the inter-

page_text: position of the arch the crucible would be broken by the direct contact of the
flame.
.
I will now describe the manner of working this galvanic vapour furnace,
which is as follows, that is to say:-In the first place, the pieces of metal
which have undergone the process of operating are to be carefully placed in
the vapour furnace V and in the condensing flue H, so as not to touch each
other. The pieces are to be introduced through the iron doors, of which a
suitable number must be made in the ends and sides of the said flue and
furnace. When the furnace and flue are charged with the desired quantity of
pieces of metal, the doors are to be carefully closed and luted, to hinder the
vapour from coming out during the process; before closing the vapour furnace,
one hundred pounds of zinc must be put into the crucible J, through the
door R, seen in the front elevation D; a fire now is to be lighted in the
furnace F, and the damper No. 8 is to be opened, and must remain open until
the galvanic vapour furnace has acquired a heat sufficient to melt lead, when
the damper is to be closed, and that of No. 7 is to be. opened, and kept open
until the end of the process, which now in reality commences, and the heat of
the said furnace must be inward, so as to cause the zinc to burn or deflagrate,
and this heat must be kept up during four hours. The fire is then to be
allowed to go out, and the damper of the chimney to be closed, when the
process will be finished; the greater or less success of which will depend upon
the person who will superinted the fire; which ought to be kept up with
great regularity, communicating with the chimney during the process, and
from time to time it will be of advantage to put a small quantity of green or
fresh cut wood or bark into the furnace F. It will have succeeded satis-
factorily if the metal have assumed a dull bluish color, resembling laminated
zinc. The furnace must be left to cool, after which it is to be opened and the
pieces of metal taken out, and the sublimated zinc which adheres about the
furnace, and more particularly about the walls of the condensing flue, ought
to be carefully collected. The pieces of metal, as soon as taken out of the
furnace, may be covered with a thick coating of good paint or varnish of any
color required.
And whereas having now particularly described my said improvements in
preparing metals for preventing oxidation, I declare that I do not claim as my
Invention the system or machines used in the process of grinding or roughing
the metals, nor do. I claim as my Invention the covering of the said metal
with varnish or paint; but I claim as my Invention,-
Firstly, the process of the conservative bath herein-before described, and as
applied to the metals after rough grinding.

page_text: Secondly, I claim as my Invention the process of operating upon metals by
means of the operating zine wheel, the zinckers, and the lumps, the whole as
herein-before described and as applied to the zincking of metal.
And thirdly, and lastly, I claim the process which I call the galvanic process;
together with the galvanic vapour furnace, as herein-before described, and as
may be seen by reference to the Drawing here annexed and as applied for the
-preparation of metals according to the manner aforesaid.
And such my Invention, to the best of my knowledge and belief, being
new and never before used in that part of Her Majesty's United Kingdom
of Great Britain and Ireland called England, Her said Dominion of Wales, or
Town of Berwick-upon-Tweed, I do hereby declare this to be my Specification
of the same, and I do verily believe that this my said Specification doth com-
ply 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 my said Invention.
In witness whereof, I, the said Thomas Dowling, have hereunto set my
hand and seal, this 20th day of July, One thousand eight hundred and