CERTAIN IMPROVE- MENTS IN THE PROCESS OF ENGRAVING. ON METALS BY MEANS OF VOLTAIC ELEC TRICITY
Year: 1840

page_text: SPENCER AND WILSON'S SPECIFICATION.
4
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, THOMAS
SPENCER, of Liverpool, in the County of Lancaster, Carver and Gilder, and
JOIN WILSON, of Liverpool aforesaid, Lecturer on Chemistry, send greeting.
WHEREAS Her present Majesty Queen Victoria, by Her Letters Patent
under the Great Seal of the United Kingdom of Great Britain and Ireland,
bearing date at Westminster, the Seventh day of October now last past, did give
and grant unto us, the said Thomas Spencer and John Wilson, Her special
licence, fullpower,soleprivilegeand authority,that we, the said Thomas Spencer
and John Wilson, our executors, administrators, and assigns, or such others as
we, the said Thomas Spencer and John Wilson, our executors, administrators,
or assigns, should at any time agree with, and no others, from time to time
and at all times thereafter 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, our Invention of "CERTAIN IMPROVE-
MENTS IN THE PROCESS OF ENGRAVING. ON METALS BY MEANS OF VOLTAIC ELEC
TRICITY;" in which said Letters Patent there is contained a proviso, obliging
us, the said Thomas Spencer and John Wilson, by an instrument in writing
under our hands and seals, or under the hand and seal of one of us, par-
ticularly to describe and ascertain the nature of our said Invention, and in what
manner the same is to be performed, and to cause the same 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 Letters Patent, as in and by the
same, reference being thereunto had, will more fully and at large appear.
[Price 8d1

page_text: NOW KNOW YE, that in compliance with the said proviso, we, the said
Thomas Spencer and John Wilson, do hereby declare that the nature of our
said Invention, and the manner in which the same is to be performed, is par-
ticularly described and ascertained in and by the Drawings hereunto annexed,
and as follows, that is to say :-
Metallic surfaces are generally engraved either by means of a graving tool,
or etched by acids. We claim the application of voltaic electricity for the
purpose of engraving metallic surfaces generally. When the metallic surface
to be engraved is copper, it must receive a coating of varnish or other pro-
jecting substance. We prefer the composition usually termed etching-ground.
The required drawing or design is then made with a pointed instrument, care
being taken that the metallic surface be fully exposed where the lines or points
are required. The surface thus prepared must now be put into communica-
tion with the copper or negative end of a voltaic arrangement, by means of a
wire or a slip of metal, and then placed in a vessel containing a solution of
sulphate of copper. Another copper plate or piece of copper wire must, in
like manner, be made to communicate with the positive end of the 'voltaic
apparatus, and must then be placed in the same vessel with the plate to be
engraved. The circle being thus completed, the electric current will remove
or bite out the metal from those parts of the plate which are not covered by
the etching ground or varnish. When the surface to be engraved is in the
form of a cylinder we place it within a hollow cylindrical piece ofmetal, which
latter serves as the surface C in vessel B, N° 1 in the Drawing. The distance
of the two plates regulates the depth and width of the lines or points; these are
also influenced by the quantity and intensity of the electricity employed, and of
the time allowed for action. The electric apparatus employed may consist
either of a single pair of plates, or of a greater number. The size of the
plates of the voltaic apparatus employed depends on the size of the plate
or other surface to be engraved. In general we find that it is convenient to
have the surface of the copper plate of the voltaic apparatus about the size of
the plate to be engraved, and the plate C in vessel B, N° 1, in the Drawing
hereunto annexed must have a surface about equal to the surface exposed in
the metallic surface D. In general we find that the plates or other surfaces
C and D may be conveniently placed two or three inches apart; when placed
at greater distances more time is required for the action. During the process
the engraved plate may be withdrawn and examined to see whether the lines
are of the required depth; if not sufficiently deep, the plate can again be
placed in the apparatus and a greater depth be obtained. When some of the
lines are required to be fainter than others, such parts of the design may be
+

page_text: stopped out in the same manner as in the com mon process of etching. In the
Drawing hereunto annexed, N° 1, A represents a vessel containing the plates
of a voltaic arrangement, which may be excited by any of the methods at
present in use. B; a separate vessel, containing the solution of sulphate of
copper, or other salt, and the surfaces C and D ; C being the conducting
surface, which is placed opposite the metallic surface to be engraved, and
which communicates with the zinc or positive end of the voltaic apparatus.
A, D, contained in the same vessel, is the surface to be engraved, and which
communicates with the negative end of the voltaic battery. In N° 1, P
represents the zinc or positive plate, and N the copper or negative end.
Another and simple form of the apparatus is represented in Drawing N° 2;
A, a vessel containing a solution of any neutral, or acidulous, or non-metallic
salt, into which the metallic surface B to be engraved is immersed, and which
must be connected by a conductor, such as a slip of metal with a surface electro
negative in regard to the surface to be engraved. In general platinum may be
employed for this purpose. A prepared metallic surface may be engraved
even without the metallic contact with the voltaic battery, as described above,
by placing it in a solution between the plates forming the poles or ends of the
voltaic apparatus. When a surface of steel is to be engraved, we prepare it
with the etching ground, and proceed in the same manner as when copper is
engraved, but in the vessel B, N° L, into which the steel is introduced, we place
a solution of common salt, aud substitute a plate or wire, or steel, or iron, or
any conducting substance, in place of the copper plate employed in the former
process. Instead of the solution of common salt, other solutions of alkaline
earthy, or metallic salts may be used. When we engrave a silver surface, we
place a silver plate by preference, or wire, in the vessel B, along with a solu-
tion of sulphate of soda, or of sulphate of silver. When we engrave a surface
of gold we employ a solution of hydrochloric acid, or a solution of a soluble
chloride, and place along with it in the vessel B a plate or wire of gold. The
other metallic surfaces may be engraved by processes in every respect similar
to those described above. We do not claim the use of any particular form of
voltaic or galvanic apparatus, nor of the particular solutions specified above.
But we claim the use or application of voltaic electricity for the purpose of
engraving metallic surfaces generally.
In witness whereof, we, the said Thomas Spencer and John Wilson
have hereunto set our hands and seals, this Sixth day of April, in
the year of our Lord One thousand eight hundred and forty-one.
THOMIS SDENCED

page_text: HENRY HIME, & Mastor
Chancery.
Extraordinary
in
AND BE IT REMEMBERED, that on the same Sixth day of April, in
the year above mentioned, the aforesaid Thomas Spencer and John Wilson
came before our Lady the Queen in Her Chancery, and acknowledged the
Specification aforesaid, and all and every thing therein contained, in form
above written. And also the Specification aforesaid was stamped according
to the tenor of the Statute in that case made and provided.
Inrolled the Seventh day of April, in the year above written.