IMPROVEMENTS IN OBTAINING LIGHT BY ELECTRICITY
Year: 1857

page_text: LETTERS PATENT to Charles Weightman Harrison, of Woolwich, in the
County of Kent, Engineer, for the Invention of "IMPROVEMENTS IN
OBTAINING LIGHT BY ELECTRICITY."
Sealed the 17th November 1857, aud dated the 20th May 1857.
PROVISIONAL SPECIFICATION left by the said Charles Weightman
Harrison at the Office of the Commissioners of Patents, with his Petition,
on the 20th May 1857.
I, CHARLES WEIGHTMAN HARRISON, of Woolwich, in the County of Kent;
Civil Engineer, do hereby declare the nature of the said Invention for "IM-
PROVEMENTS IN OBTAINING LIGHT BY ELECTRICITY," to be as follows:-
I obtain electric- light by causing electricity of any suitable degree of
power to pass through, decompose, or vaporise compounds of metal with
other elementary bodies, such as the metallic oxides, chlorides, fluorides,
sulphides, and similar combinations, whether found in nature or prepared
artificially; also the 'metallic salts, both acid, alkaline, and neutral. These
are for the most part in their ordinary solid state classed as noncon-
ductors of electricity, but when rendered fluid by heat, they, with some
exceptions, acquire a high degree of conducting power. I therefore fuse or
liquify such of these substances, as are capable of becoming conductors, by the
application of heat, either derived from an electric current or other means,
and then by any suitable arrangement or contrivance, I cause a small stream

page_text: orstreams, or drops of such melted compound to form a portion of the electric
circuit, or to pass through or within that part of its course where the electricity
in motion is subject to great resistance. By this means the compound under-
goes decomposition or molecular modifications according to its nature, and at
the same time yields a luminous effect of, in some cases, the most brilliant
kind.
I likewise obtain electric light from a stream or streams of melted metal or
melted compound of two or more metals. For this purpose I prefer to use
those metals which assume a fluid form at comparatively low degrees of heat,
such as potassium, sodium, tin, bismuth, lead, zinc, &c.; or I use compounds
of metals which can be made fluid at low degress of heat, like the alloys
known as fusible metal. I cause such stream or streams of fused metal, by
any convenient arrangement, to form part of an electric circuit, whereby the
flowing metal may be partly or wholly vaporised or changed, and light
produced.
Instead of a flowing or stream electrode, I sometimes employ a reservoir of
a melted or fluid body as the positive electrode, and I use therewith a carbon
or solid metal self-regulating negative electrode. I form the reservoir of
glass, and cover the fluid electrode contained therein with a float or ring made
of
any suitable infusible material, so as to confine evaporation to a central
aperture in the float.
When it is desirable to inclose the light in a tube or shade of glass, I con-
struct the apparatus so that the rarefied air or vapor may serve to heat the fused
electrode. I also make suitable arrangements for retaining or condensing the
vapors arising from such of the herein-before named bodies which it may be
desirable to preserve.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Charles Weightman Harrison in the Great Seal Patent
Office on the 20th November 1857.
TO ALL WHOM THESE PRESENTS SHALL COME, I, CHARLES
WEIGHTMAN HARRISON, of Woolwich, in the County of Kent, Civil Engineer,
send greeting..
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twentieth day of May, in the year of our Lord,
One thousand eight hundred and fifty-seven, in the twentieth year of Herreign,
did, for Herself, Her heirs and successors, give and grant unto me, the said

page_text: Charles Weightman Harrison, Her special licence that I, the said Charles
Weightman Harrison, my executors, administrators, and assigns, or such
others as I, the said Charles Weightman Harrison, my executors, adminis-
trators, 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 OBTAINING LIGHT BY ELECTRICITY," upon the
condition (amongst others) that I, the said Charles Weightman Harrison,
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 per-
formed, 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.
NOW KNOW YE, that I, the said Charles Weightman Harrison, 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 thereof (that is to say) :-
I obtain electric light by causing electricity of any suitable degree of power
'to pass through, decompose, or vapourize compounds of metal with other
elementary bodies, such as the metallic oxides, chlorides, fluorides, sulphides,'
and similar combinations, whether found in nature or prepared artificially; also'
the metallic salts, both acid, alkaline, and neutral. These are for the most
part in their ordinary solid state classed as non-conductors of electricity, but
when rendered fluid by heat, they, with some exceptions, acquire a high degree
of conducting power. I therefore fuse or liquify such of these substances, as
are capable of becoming conductors by the application of heat, either derived'
from an electric current or other means, and then by any suitable arrangement
or contrivance, I cause a small stream or streams, or drops of such melted
compound to form a portion of electric circuit, or to pass through or within
that part of its course where the electricity in motion is subject to great
resistance. By this means the compound undergoes decomposition or mole-
cular modifications according to its nature, and at the same time yields a
luminous effect of, in some cases, the most brilliant kind.
I likewise obtain electric light from a stream or streams of melted metal or
melted compound of two or more metals. For this purpose I prefer to use
those metals which assume a fluid form at comparatively low degrees of heat,
such as potassium, sodium, tin, bismuth, lead, zinc, &c.; or I use compounds

page_text: of metals which can be made fluid at low degrees of heat, like the alloys
known as fusible metal. I cause such stream or streams of fused metal, by
any convenient arrangement, to form part of an electric circuit, whereby the
flowing metal may be partly or wholly vapourized or changed, and light
produced.
Instead of a flowing or stream electrode, I sometimes employ a reservoir of
a melted or fluid body as the positive electrode, and I use therewith a carbon
or solid metal self-regulating negative electrode. I form the reservoir of glass,
and cover the fluid electrode contained therein with a float or ring made of
any suitable infusible material, so as to confine evaporation to a central
aperture in the float.
When it is desirable to inclose the light in a tube or shade of glass, I
construct the apparatus so that the rarefied air or vapor may serve to heat the
fused electrode. I also make suitable arrangements for retaining or con-
densing the vapours arising from such of the herein-before named bodies which.
be desirable. to preserve.
may
it
I perform that portion of this my Invention which relates to the employ
ment, as electrode, of a stream or streams of melted metal or metals, or:of
melted compounds of metal with other elementary bodies, by placing a supply
of such of these substances that I desire to use in a reservoir, which is so
constructed and placed that the contents may be readily heated by a passing"
current of electricity or by steam, or vapour, or by hot water or any other
convenient means which will produce liquifaction in such substances. Ithen
cause a stream of the melted electrode to flow through an orifice in the
reservoir, the volume of the stream being proportionate to the power of the
electricity employed, and this again having relation to the amount of light
required, and to the nature of the substance; or substances forming the
electrodes. In the line of the stream or approaching thereto, and at any
suitable distance from the orifice whence it issues, I place a pencil or disc of
carbon or other conducting substance, or a reservoir of metal, upon or near
to which the escaping stream will flow. I connect the stream electroed with
one of the poles, as for instance, the negative of a.voltaic or other battery,
and the carbon or second electrode with the other pole, so that on the passage
of the current the light may be produced at or about the point where they
would, if not moved away, come in contact one with the other.
Such substances as admit of being made fluid by the heat arising from the
passage through them of a current of electricity (of sufficient power to
produce a light equal to all ordinary illuminating requirements), I prefer to
form into pencil electrodes of about the sixth part of an inch in diameter;

page_text: and of any required length, the point being cut fine. I place an electrode of
this kind in a clay or glass tube, the aperture being adapted to its size,
leaving a small space for the introduction of the end of a copper slide rod,
which I put in for the purpose of preserving contact with the electrode as it
diminishes. A small orifice forms the mouth of the tube through which the
point of the electrode passes, so as to form contact with the second electrode,
and thus complete the circuit of the current within the lamp when arranged
for operation. The electricity is conveyed to the slide rod by a metal guide
cap or frame fixed on the end of the tube, and joined to one of the wires:
from the battery. Amongst the various metals and metal compounds or
alloys which I have found suitable to be employed in this manner, and to
afford the most brilliant light, are the following, namely, metals, potassium,
sodium, zinc, tin, lead, and bismuth. Metal compounds or alloys,-first, equal
parts of sodium and zinc; second, three parts tin and one part lead; third;
equal parts each of zinc, bismuth and lead; fourth, two parts bismuth, one
part tin and one part lead; fifth, three parts.lead, one part tin and one-part
sodium; and sixth, eight parts bismuth, five parts lead,three parts tin, and one.
part mercury.
When it is convenient to fuse electrodes by the heat derived from other
sources than that of the electric current, such as the waste steam of an
engine, or the heated vapours of a furnace, I'nse either a tubular or any other
kind of reservoir which is fit for the purpose. To the bottom of the reservoir
I attach a short pipe, by which the fluid electrode is led to the lamp, where, as
it issues through a small regulated orifice, it forms a stream electrode. Besides
the various metals and alloys of metals herein-before enumerated,.other less
readily fusible metals and alloys may in this manner be employed, according
to the degrees of heat to which they are intended to be subjected...
Of the different compounds of metals with other elementary bodies which. I.
have employed in the production of electric light, I.prefer amongst the oxides
to use the peroxide, and the protoxide of potassium, and the mixed protoxides
of potassium and sodium in about equal portions of each. Amongst the.
chlorides I have employed the double chlorate of sodium and alluminium; ofi
the fluorides that of lead; and of the sulphides that of copper, which yields a
a fine green light. Of the metallic salts I have used the mixed carbonates of
potash and soda, in the proportion of five parts of the former to four parts of
the latter. The fused nitrate and chlorate of potash may also. be successfully
employed. I do not, however, limit myself to the. use of the substances.or
compounds which I have herein named, as other metals, alloys, ainalgams;,
oxides, salts, and such like combinations may, when rendered fluid by heat, be

page_text: used with good effect, as stream electrodes, for the production of light by
electricity.
As a negative or second electrode, I generally employ a solid body, such as
carbon or one of the metals, but I prefer to use two pencil carbon electrodes
in combination with one positive stream-electrode, and to arrange these in a
right line, one on each side of the stream. By this method the stream may
be intersected at any desired point, and the light obtained with great regularity.
I sometimes use a stream or a reservoir of a fluid body for the negative elec-
trode, and I so regulate its distance from the positive stream electrode, that
when they are about to come into contact, the circuit of the current may be
broken, and the light produced. A stream electrode being liable to derange
ment from the agitation of the air, I place over it, as a protection, a tube of
glass of any convenient size, leaving one or more apertures at each end, by
which the heated vapours may be directed around the flowing electrode, and
when it is desirable I connect the upper end of the glass tube with a pipe
proceeding to a receiver of any suitable kind, so as to carry away and condense
the vapours.
When I obtain electric light by employing a reservoir of a fluid body as the
positive electrode, I use a cylindrical glass vessel, wherein I pour a supply of
mercury; upon this I place a float made of a conical shape, and formed so
that its base may accurately fit within the reservoir. This float may be made
of refractory clay, or of platinum, or other material, a small aperture being
formed through it from the apex to the base. Into this aperture the mercury
is impelled so as to fill it, or nearly so, either by the weight of the float itself
or by other pressure. I then fix a frame or case over the reservoir, so as to
carry a tube which is free to work in a vertical position, the motion being
given or controlled by an electro-magnet and keeper, or by a helex of the con-
ducting wire. In this tube I place a carbon pencil electrode, its point being
brought down to the mouth of the float, and forming contact with the mercury.
On connecting a voltaic battery with the apparatus so as to complete the
circuit of its current by rendering the mercury positive and the carbon nega-
tive, the latter is moved away from the mouth of the float, and the light
produced. The evaporation or consumption of the mercury is confined to the
central aperture in the float, and this being kept full by pressure affords a
constant supply of this electrode. As the carbon electrode diminishes it
approaches the mouth of the float by self-acting small periodic advances, thus
preserving a very constant degree of separation between the electrodes. The
construction of electro-mechanical motions of this kind are well understood.
In place of mercury other fluid may be used as the positive electrode, or a

page_text: solid body may by convenient means be kept melted, and in that state made to
flow within the aperture of the float.
Having thus described the nature of my said Invention, and the manner of
performing the same, I declare that I do not confine myself to the details
herein set forth, as they may be varied without departing from my Invention;
but what I claim is,-
First, the manufacture and employment of electrodes of melted compounds
of metal with other elementary bodies, as herein-before described.
Second, the manufacture and employment of electrodes of melted metal, and
of compounds of two or more metals when made fluid by heat, as herein-before
described.
And, third, the construction and employment of a float in combination
with a reservoir of a fluid electrode, whereby evaporation or consumption
of such electrode by the light is confined to an aperture therein, as herein
described.
In witness whereof, I, the said Charles Weightman Harrison, have here.
unto set my hand and seal, this Twentieth day of November, One
thousand cight hundred and fifty-seven.
CHAS W. HARRISON. (L.s.)