IMPROVEMENTS IN METALLIC ALLOYS AND IN THEIR APPLICATION TO IRON SURFACES
Year: 1872

page_text: LETTERS PATENT to George Hand Smith, of the City and State of
New York, United States of America, now of No. 8, Southampton
Buildings, London, Gentleman, for the Invention of "IMPROVEMENTS
IN METALLIC ALLOYS AND IN THEIR APPLICATION TO IRON SURFACES FOR
Sealed the 23rd April 1872, and dated the 28th February 1872.
PROVISIONAL SPECIFICATION left by the said George Hand Smith at
the Office of the Commissioners of Patents, with his Petition, on
the 28th February 1872.
I, GEORGE HAND SMITH, of the City and State of New York, United
States of America, now of No. 8, Southampton Buildings, London,
Gentleman, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN METALLIC ALLOYS AND IN THEIR APPLICATION TO IRON SURFACES
FOR PREVENTING THE CORROSION OF THE SAME, " to be as follows:-
The object of my said Invention is the protection of iron surfaces
from corrosion by establishing a weak galvanic current over the same.

page_text: This object is accomplished by applying to the metal an alloy which is
electro-positive to the iron, so that the latter is saved at the expense
of
the alloy, that is to say, the corrosion is confined solely to the alloy and
does not attack the iron. I am aware that it has been heretofore
proposed to protect iron by the application to its surface of an electro-
positive metal or alloy, but in practice this method of protection has
not been successful, chiefly because of the rapid destruction of the
protecting metal and the cost and inconvenience of frequently renewing
the same.
My said Invention is more especially designed for the protection of
iron from oxidation or corrosion in the atmosphere, or in salt or fresh
water, bilge water, or water charged with organic impurities, but it is not
designed to afford protection against the action of powerful acids or
strong saline solutions like those used in powerful galvanic batteries, or
such as are manufactured for chemical or other special purposes. Some
of its most important applications are for the protection of the surfaces
of iron ships, the preservation of iron pipes or tubes for conveying
water, and the tubes or other parts of steam boilers for keeping sweet
or pure the bilge water of ships, for preserving water tanks and keeping
the water sweet, for the preservation of anchors, chains, rudders, pumps,
and for many other like purposes.
I use an alloy composed of two metals, one of which is electro-
positive and the other electro-negative to the iron. These two metals
are combined in such proportions that the alloy is electro-positive to the
iron, but only to such an extent that when the iron is exposed to the
influences above specified the destruction of the said alloy is reduced
to a minimum, or in other words will proceed so slowly as to be prac-
tically of no importance, and while complete protection is afforded to
the iron the alloy when once applied to the same will not require renewal
for a very long time.
I prefer that the aforesaid alloy should be composed of zinc and tin
in equal proportions. In this alloy the zinc is electro-positive and the
tin electro-negative to the iron, and when these two metals are combined
in equal proportions by weight the alloy will be sufficiently electro-
positive to afford the required protection to the iron, while its own
decomposition or corrosion will be very slow.
The superficial area of the alloy may be in about the proportion of

page_text: one to one hundred and forty-four to that of the iron, and in some cases
it may be as much as two to one hundred and forty-four. The alloy is
applied to the surface to be protected in strips or pieces at such intervals
apart as will be found efficient and convenient. It may be attached to
the iron by riveting, screwing, or other like means, or it may sometimes
be soldered on the iron provided the solder used is not so made or applied
as to create a third voltaic element.
filed by the said George Hand Smith in the Great Seal Patent Office
on the 28th August 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
HAND SMITH, of the City and State of New York, United States of
America, now of No. 8, Southampton Buildings, London, Gentleman,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-eighth day of February, in the
year of our Lord One thousand eight hundred and seventy-two, in the
thirty-fifth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said George Hand Smith, Her special licence
that I, the said George Hand Smith, my executors, administrators, and
assigns, or such others as I, the said George Hand Smith, 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 METALLIC
ALLOYS AND IN THEIR APPLICATION TO IRON SURFACES FOR PREVENTING THE CORRO-
SION OF THE SAME," upon the condition (amongst others) that I, the said
George Hand Smith, my executors or administrators, by an instrument
in writing under my, or their, or one of their hands and seals, should
particularly 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 immediately after the date of the said Letters Patent.

page_text: NOW KNOW YE, that I, the said George Hand Smith, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement :-
The object of my said Invention is the protection of iron surfaces
from corrosion by establishing a weak galvanic current over or through
the same. This object is accomplished by applying to the metal an
alloy which is electro-positive to the iron, so that the latter is saved at
the expence of the alloy, that is to say, the corrosion is confined solely
to the alloy and does not attack the iron. I am aware that it has been
heretofore proposed to protect iron by the application to its surface of
an electro-positive metal or alloy, but in practice this method of pro-
tection has not been successful, chiefly because of the rapid destruction
of the protecting metal and the cost and inconvenience of frequently
renewing the same.
I use an alloy composed of two metals, one of which is electro-
positive and the other electro-negative to the iron, or both metals may
be electro-positive to the iron and one electro-negative to the other.
These two metals are combined in such proportions that the alloy is
electro-positive to the iron, but only to such an extent that when the
iron is exposed to the influences herein specified the destruction of the
said alloy is reduced to a minimum, or in other words will proceed so
slowly as to be practically of no importance, so that while complete
protection is afforded to the iron the alloy when once applied to the
same will not require renewal for a very long time. I may use more
than two metals in the composition of the said alloy, that is to say, I
may use more than one electro-positive metal and more than one electro-
negative metal, but in all cases they must be combined in such
proportion that the alloy will be electro-positive to the iron.
I prefer that the aforesaid alloy should be composed of zinc and tin
in equal proportions. In this alloy the zinc is the electro-positive and
the tin the electro-negative metal, and when these two metals are com-
bined in equal proportions by weight the alloy will be sufficiently
electro-positive to the iron to afford the required protection to the same,
while its own decomposition or corrosion will be very slow. The above
proportions may however be varied according to the result desired to be
obtained. In some instances it may be necessary to increase the

page_text: galvanic or voltaic action, for which purpose I increase the proportion
of zinc or other electro-positive metal or metals in the alloy, while on
the other hand if it is desired to diminish the galvanic action I increase
the proportion of tin or other electro-negative metal or metals in the
said alloy.
The superficial area of the alloy may be in about the proportion of
one to one hundred and forty-four to that of the iron, and in some cases
it
may
be as much as two to one hundred and forty-four. The alloy is
applied to the surface to be protected in strips or pieces at such intervals
apart as will be found efficient and convenient. It may be attached to
the iron by rivetting, screwing, or other like means, or it may sometimes
be soldered on the iron provided the solder used is not so made or applied
as to arrest or disturb the desired voltaic or galvanic action.
My said Invention is more especially designed for the protection of
iron from oxidation or corrosion in the atmosphere, or in salt or fresh
water, bilge water, or water charged with organic impurities. It will
not in all cases afford protection against the action of powerful acids or
strong saline solutions, such as are manufactured for chemical or other
special purposes, although it may sometimes be advantageously used in
some operations wherein such acids or solutions are contained in or
passed through iron vessels or apparatus. Some of its most useful
applications are for the protection of the surfaces of iron ships, the
preservation of iron pipes or tubes for conveying water, and the tubes
or other parts of steam boilers, for keeping sweet or pure the bilge water
of ships, for preserving water tanks and keeping the water sweet, for the
preservation of anchors, chains, rudders, pumps, and for many other
like nurnoses.

page_text: connection with iron the said alloy is electro-positive to the iron, but
the action due to its electro-positive element is controlled or reduced by
its electro-negative element for the purposes set forth.
In witness whereof, I, the said George Hand Smith, have hereunto
set my hand and seal, this Twenty-eighth day of August, in the 5
year of our Lord One thousand eight hundred and seventy-two.
Witness,
W. J. LowE.
GEORGE HAND SMITH. (L.S.)