IMPROVEMENTS IN MEANS OR APPARATUS FOR PREVENTING THE CORROSION AND FOULING THE BOTTOMS OF IRON AND STEEL SHIPS AND METAL-SHEATHED OF WOODEN PROVISIONAL SPECIFICATION AND ALSO APPLICABLE TO PROPELLERS AND OTHER PARTS
Year: 1883

page_text: LETTERS PATENT to James Ballantyne Hannay, of Glasgow, in the County
of Lanark North Britain, Chemist, for an Invention of "IMPROVEMENTS IN
MEANS OR APPARATUS FOR PREVENTING THE CORROSION AND FOULING
THE BOTTOMS OF IRON AND STEEL SHIPS AND METAL-SHEATHED
OF
WOODEN
PROVISIONAL SPECIFICATION left by the said James Ballantyne Hannay
at the Office of the Commissioners of Patents on the 12th September 1888.
JAMES BALLANTYNE HANNAY of Glasgow, in the County of Lanark, North
Britain, Chemist "IMPROVEMENTS IN MEANS OR APPARATUS FOR PREVENTING
THE CORROSION AND FOULING OF THE BOTTOMS OF IRON AND STEEL SHIPS AND
METAL-SHEATHED WOODEN SHIPS AND ALSO APPLICABLE TO PROPELLERS AND
OTHER PARTS
"
This Invention has for its object to prevent the corrosion and fouling of the
bottoms of iron and steel ships and metal-sheathed wooden ships, and is also
applicable to propellers and other parts
In carrying out the Invention the bottom of an iron or steel ship is kept clean
or uncoated with any paint or composition and it is rendered electro-negative by
fixing upon it one or more plates or blocks of zinc of comparatively small size.
The zinc is placed so as to be immersed in or wetted by the water in which the
sbip floats. In the action which is intended to take place the zinc gradually
corrodes and an electric current is produced through it and the iron or steel,
rendering the latter electro negative. The iron or steel is thus preserved at the
expense of the zinc which has to be renewed from time to time as it becomes
corroded or consumed. It is important and essential to connect the zinc to the
iron or steel by means of solder in order to insure the proper action taking place
and to render it sufficient and permanent. Mere contact such as is obtainable by
bolting or similar means is insufficient; or if partially efficient when the zinc is

page_text: freshly applied, rapidly becomes defective. The complete union by soldering is
also necessary to secure the proper action of the zinc which without such union is
liable to become coated with an adherent film of oxide which masks and diminishes
the action, whereas any oxide formed under proper conditions is of a loose and
permeable character and does not interfere with the electric action. The zinc is by
preference employed in a dense condition such as is obtained by rolling it and
when a very energetic action is desired its outer surface may be amalgamated or
instead of being treated for that purpose with mercury alone it may be treated
with an amalgum of mercury and sodium. In the generality of cases the zinc will
answer satisfactorily without being amalgamated
In the case of metal sheathed wooden ships the zinc is to be applied to the metal
sheathing in precisely the same way as to the bottoms of iron or steel ships. And
in the cases of propellers and other parts comparatively small plates or blocks are
to be attached by soldering them on in convenient positions. In all cases where a
number of metal plates or sheets are joined together and proposed to be protected
by means of pieces of zinc attached as described, complete conductive union must
be secured between the several plates or sheets by soldering or other effective
means.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said James Ballantyne Hannay in the Patent Office on the 7th March
1884.
JAMES BALLANTYNE HANNAY, of Glasgow, in the County of Lanark, North
Britain, Chemist "IMPROVEMENTS IN MEANS OR APPARATUS FOR PREVENTING
THE CORROSION AND FOULING OF THE BOTTOMS OF IRON AND STEEL SHIPS AND
METAL-SHEATHED WOODEN SHIPS AND ALSO APPLICABLE TO PROPELLERS AND
OTHER PARTS
"
My said Invention has for its object to prevent the corrosion and fouling of the
bottoms of iron and steel ships and metal-sheathed wooden ships, and is also
applicable to propellers and other parts.
In carrying out the Invention the bottom of an iron or steel ship is kept clean or
uncoated with any paint or composition and it is rendered electro-negative by
fixing upon it one or more plates or blocks of zinc of comparatively small size.
The zinc is placed so as to be immersed in or wetted by the water in which the
ship floats. In the action which is intended to take place the zino gradually
corrodes and an electric current is produced through it and the iron or steel,
rendering the latter electro-negative. The iron or steel is thus preserved at the
expense of the zinc which has to be renewed from time to time as it becomes
corroded or consumed. It is important and essential to connect the zinc to the
iron or steel by means of solder in order to insure the proper action taking place
and to render it sufficient and permanent. Mere contact such as is obtainable by
bolting or similar means is insufficient, or if partially efficient when the zinc is
freshly applied, rapidly becomes defective. The complete union by soldering is
also necessary to secure the proper action of the zinc which without such union is
liable to become coated with an adherent film of oxide which masks and diminishes
the action, whereas any oxide formed under proper conditions is of a loose and
permeable character and does not interfere with the electric action. The zinc is by
preference employed in a dense condition such as is obtained by rolling it; and
when a very energetic action is desired its outer surface may be amalgamated or
instead of being treated for that purpose with mercury alone it may be treated
with an amalgam of mercury and sodium. In the generality of cases the zinc will
answer satisfactorily without being amalgamated.
In the case of metal-sheathed wooden ships the zinc is to be applied to the
metal sheathing in precisely the same way as to the bottoms of iron or steel ships.
And in the cases of propellers and other parts comparatively small plates or blocks
are to be attached by soldering them on in convenient positions. In all cases
where a number of metal plates or sheets are joined together and proposed to be
protected by means of pieces of zinc attached as described, complete conductive
union must be secured between the several plates or sheets by soldering or other
effective means.
I find that a piece of zinc of sufficient size and when effectively soldered as
herein before described exerts a protective influence to a distance of about twenty
feet in all directions from it; and in applying the zinc to ships' bottoms I consider
it preferable to place the pieces of zinc at less distances apart than forty feet. In
the case of iron or steel ships built in the very common way with alternate inner
and outer strakes; each zinc piece may be very conveniently of a size to fit in
between two of the outer strakes; and it may be of a square form and one and a
half to two inches thick. In the case of a propeller blade the zinc pieces, on
which, may be subjected to considerable friction, and in other cases when considered
desirable the zinc pieces may be soldered at other parts besides their edges. For

page_text: this purpose spots on the iron steel or other metal and on the inside of the zing
may be cleaned and tinned and pieces of solder applied; and then, the zinc being
placed in position, but having no holes in it, a blow-pipe flame or a soldering bolt
may be applied to the outside of the zinc and the heat being transmitted through
the zinc will soften the solder and cause adhesion.
Having thus particularly described my said Invention and the manner of
performing the same I have to state that I do not restrict myself to the precise
details herein before described but that what I believe to be novel and original and
claim as the Invention secured to me by and in terms of the herein before in part
recited Letters Patent is :-
Applying zinc in the improved manner herein before described for preventing the
corrosion and fouling of the bottoms of iron and steel ships and metal-sheathed
wooden ships, and of propellers and other parts.
In Witness whereof I, the said James Ballantyne Hannay, have hereunto set
my hand and seal this sixth day of March in the year of our Lord One thousand
eight hundred and eighty-four.
Witness
EDMUND HUNT
Patent Agent
Glasgow.
JB HANNAY
(L.S.)