IMPROVEMENTS IN LEAD PROJECTILES, AND IN THE MANUFAC- TURE THEREOF
Year: 1878

page_text: LETTERS PATENT to Sydney Pitt, of Sutton, in the County of Surrey, for the
Invention of "IMPROVEMENTS IN LEAD PROJECTILES, AND IN THE MANUFAC-
TURE THEREOF." A communication from abroad by Lewis Crooke, of the City
of New York, United States of America.
Sealed the 19th July 1878, and dated the 29th May 1878.
COMPLETE SPECIFICATION filed by the said Sydney Pitt at the Office of
the Commissioners of Patents on the 29th May 1878.
SYDNEY PITT, of Sutton, in the County of Surrey "IMPROVEMENTS IN LEAD
PROJECTILES, AND IN THE MANUFACTURE THEREOF." A communication from
abroad by Lewis Crooke, of the City of New York, United States of America.
Shot and balls for fire-arms to be used by hand are made of lead or some of its
alloys, and are generally blacked and polished by means of blacklead or graphite.
Such shot are objectionable for several reasons.
In the first place the process of blacking and polishing the shot by means of
graphite produces a dust, which is highly injurious to the workman employed to do
the manual labour.
The shot also are disagreeable to handle, and produce the rapid fouling of shot
guns. They are affected by contact with the flesh or juices of the game shot with
them, so that salts of lead are speedily produced, which are injurious to those who
eat the game.
The subject of the present Patent is a new manufacture of shot and balls, which
is free from the above stated objections, and also an improvement in the art of
manufacturing shot and balls.
The new manufacture consists of burnished tin-plated shot and balls, or in other
words of shot and balls which are both tin-plated and burnished so as to present a
bright metallic surface that does not soil the hands or the gun, and does not
produce poisonous compounds.
The improvement in the art consists of the treatment of projectiles composed in
part or wholly of lead with a solution of a salt of tin, and with agitation, either

page_text: separately or conjointly, the effect of the first named treatment being the coating or
plating of the shot with tin, and the effect of the second named treatment being the
burnishing of the plated shot.
In order that the Invention may be fully understood, the following description is
given of the best mode thus far devised by the inventor of producing the said new
manufacture.
When tin-plated shot are to be made, the lead shot are taken in the damp con-
dition in which they exist when removed from the cistern of the shot tower before
they have had time to become oxydized, and are treated either simultaneously or
consecutively with an acid solution of a salt of tin and with agitation sufficient to
burnish them.
The said solution of tin which the inventor has used with the best success is
made of the following ingredients and of the following proportions, the quantity
made at any one time being varied as found expedient-One pound of crystallized
protochloride of tin is dissolved in eight gallons of water, and three-quarters of a
pound of commercial nitric acid are added to the solution. The shot to be treated
are charged into a tumbling barrel or other mechanical agitator lined with glass or
other material having a smooth vitrified surface, and a sufficient quantity of the
compound acid solution is added to fill the interstices between the shot and just
cover them. The tumbling barrel is then closed, and is agitated briskly until
metallic tin is deposited from the solution upon the shot in the form of a plating
or thin coat therefore.
The rapid agitation of the shot in the glass surfaced barrel causes the consolidation
of the deposited tin-plating, and also its burnishing, so that when the work is done
the shot produced have bodies of lead or an alloy thereof coated with a highly
burnished plating of tin.
The kind of tumbling barrel which is preferred for the work is one having
trunnions transverse of its length, whereby a brisk agitation can be readily
effected.
The time required for the agitation is generally about five minutes, but may be
prolonged if deemed expedient.
If deemed expedient the process may be varied by first treating the shot or
balls with the tin solution hot or cold in any ordinary wooden tumbling barrel, or by
first treating them with the tin solution by simply steeping them without agitation
in a quantity of the tin solution sufficient to cover them, and after the shot have
been coated or plated with tin, they may be burnished by charging them with
water into a glass-lined tumbling barrel in which they are agitated until their
surfaces become burnished.
Shot which have previously been polished by the use of graphite may be used
for my new manufacture, provided they be first cleansed of the graphite and lead
oxide, and of any grease which may adhere to them.
Shot also which have laid in stock after being taken from the cistern of the shot
tower may be used, but in such case as their surfaces are generally oxydized, it is
expedient to cleanse them by agitation with a weak solution of nitric acid before
subjecting them to the tin solution.
If burnished tin plated lead balls are to be produced, they may be made by the
use of the same solution and agitation as above described for shot.
In operating with the acid tin solution above described, care should be taken
that the solution is not milky in appearance, or does not become so when applied
to the shot or balls.
If the solution be milky when made, it is an evidence that more nitric acid
should be added to it, and if it becomes milky when in contact with the shot, it is
an evidence that more of the solution should be used as well as more nitric acid.
The solution most expedient for any particular lot of shot may be readily found
by commencing the treatment with the compound solution herein-before described,
and then varying its composition as circumstances or the peculiar nature of the
lead shot shew to be expedient.

page_text: The Invention of the new manufacture is not restricted to the means above
described of producing the same, because the shot may be plated with tin other-
wise than as herein-before described, and may then have their tin-plated surfaces
burnished by agitation in a glass tumbling barrel, or in one faced or lined with
glass or its equivalent, or by the action of moving tables or plates of glass caused to
move by other means than a tumbling barrel. On the other hand the process or
improvement in the art above described by me is not restricted to the peculiar acid
solution of tin above described, as other solutions of tin may be used with success.
Thus for example, a solution of tin for coating or plating may be prepared by
dissolving one pound of proto-chloride of tin and two pounds of chloride of sodium
in eight gallons of water, to which half a pound of hydrochloric acid (commercial)
have been added, and if deemed best, the action of the solution may be aided
by heat applied by introducing steam into the tumbling barrel by means of a pipe
inserted through one of the trunnions thereof.
Another solution which produces good results is obtained by dissolving one
pound of crystallized proto-chloride of tin in one quart of water containing two
ounces of hydrochloric acid (commercial) and by then adding to the solution so
produced four gallons of a solution of bitartrate of potash acidulated with four
and a half ounces of nitric acid (commercial).
The solution of the bitartrate may contain about half a pound of the bitartrate
for the four gallons of water.
Other tin-plating solutions may be used either hot or cold as found expedient.
Lead shot previously cleansed of lead oxide may be electro-plated with tin by
heating them simultaneously with a proper solution of tin and a current of elec-
tricity obtained from a galvanic battery or by other means.
A proper solution for this purpose may be made by dissolving in two gallons
of water half a pound of pyrophosphate of soda, and by adding to the solution
one pound of crystallized proto-chloride of tin. This solution may be weakened by
the addition of water, if deemed expedient. This same solution may be used in
connection with metallic zinc without a battery. In this case the shot to be treated
are charged into an ordinary tumbling barrel with a sufficient quantity of solution
to cover them, and with a quantity of granulated zinc, which need not exceed one-
tenth of the weight of the shot. The shot are then agitated in the tumbling barrel
until the coating or plating is effected, say, for a period of ten minutes. Or in place of
charging zinc into the tumbling barrel, the latter may be formed of zinc, or may be
lined with that material. After the shot have been tin-plated by the above treatment,
they may be burnished by agitating them in an ordinary tumbling barrel with saw-
dust, or better by agitating them in a glass-lined tumbling barrel with water.
The new manufacture herein-before described is not restricted to projectiles
having bodies of pure lead, as either lead or its alloys may be employed for such
bodies.
What is claimed as the Invention is,-
The new manufacture of tin-coated lead projectiles, substantially as before set
forth.
The improvement in the art of manufacturing lead projectiles consisting substan-
tially, as before set forth, of the treatment of lead projectiles with a solution of
tin, and with agitation, whereby said projectiles are not only tin-coated, but have
bright metallic surfaces imparted to them.
In witness whereof, I, the said Sydney Pitt, have hereunto set my hand
and seal, this Twenty-second day of May, in the year of our Lord One
thousand eight hundred and seventy-eight.
SYDNEY PITT, (L.S.)