Improvements in Electric Meters.
Year: 1892

page_text: COMPLETE SPECIFICATION.
Improvements in Electric Meters.
We, ALEXANDER GEORGE MCKENNA, citizen of the United States, of
159 Robinson Street, Allegheny City, in the County of Allegheny, and State of
Pennsylvania, United States of America, Gentleman, and HENRY TOWNSEND
WEED, of 82 Robinson Street, Allegheny City, in the County of Allegheny, and
State of Pennsylvania, also a citizen of the United States, Gentleman, do hereby
declare the nature of this invention and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement:-
This invention relates to improvements in electrolytic electrometers, reference
being had to the accompanying drawings, forming part of this Specification, in
which;-
Fig. 1 shows our improved apparatus in diagram plan view.
Fig. 2 is a vertical section of the electrolytic meter-cell.
Fig. 3 represents a vertical section of a modification of the cell and a diagram-
matic view of its electrical connections.
Fig. 4 is a plan view of a switch which may be used in connection with our
apparatus.
Fig. 5 is a vertical section on the line IV-IV of Fig. 3.
The object of our invention is to improve the construction of meters in which
electric currents are measured by electrolytic action, in such manner that instead
of the tedious process of removing and weighing the electro-deposited metal,
necessary in apparatus as at present used, the indication of the amount of metal
can be noted directly by observation of a deposit which is collected and retained
in a graduated tube or receptacle. The advantage of such improvement is that
it enables the person using the meter to observe its registration at any time and
without difficulty, whereas in meters of the ordinary form, the measurement is
practically obtainable only by a skilled person who opens the instrument and weighs
the deposit.
Our improved apparatus embodies an electrolytically-acting meter, comprising
an electrolytic cell containing a suitable mercurial salt, through which the whole or
a part of the current passes, and provided with a suitable receptacle in which the
metallic mercury liberated at the cathode is collected and in which its quantity
can be measured and the indication of the meter thus obtained.
In the drawing, 2, 3, represent the main conductors of an electric circuit, used
for obtaining light or power; 4, 5, represent the conductor of a shunt circuit,
containing a suitable resistance, so that a fraction only of the current shall pass
through the same, and 6 represents an electrolytic cell. This cell may be con-
structed in various ways, but a convenient. form is illustrated in Figs. 2 and 3,
which we shall now describe.
The positive electrode consists of a layer 7 of metallic mercury into which one
of the branches of the shunt circuit conductor extends. The other electrode 8 is
preferably of a graphite pencil with which the conductor 5 is electrically connected,
and beneath the latter electrode is a graduated glass tube 9, provided with a funnel-
mouth 10 adapted to catch the electro deposit of mercury as hereinafter explained..
Instead of having the graduations marked on the tube, they may be indicated on a
separate scale 13, like a barometric scale, (as shown in Fig. 3) or the tube may be
marked to correspond to the quantity of electricity, and the scale to the price to be
charged, or vice versa.
Said tube may also have a stop cock 11 by which its contents may be drawn off.
A funnel 11 may be provided for the return of the mercury deposited in the tube 9

page_text: to the cell 6. 12 and 14 represent the means for a system of lamps, or other
electrically operated devices.
We have found that a suitable electrolyte is a solution of the soluble salt of
mercury and potassium cyanide, but the invention is not limited thereto, since other
mercurial salt solutions may be employed.
When the electrolyte is charged into the cell so as to be in contact with the two
electrodes, and an electric current passed through the main circuit, a known
fractional portion of the current will pass through the shunt.circuit and through the
cell, and by electrolytic action will cause the decomposition of the salt, depositing
at the electrode 8. metallic mercury, which will drop therefrom into the tube and
will collect therein.. A's the electrolyte is impoverished by such decomposition it
will be renewed constantly by taking up mercury from the layer of the metal in the
cell; and this latter may be replenished by returning the mercury. from the glass
tube back to the cell through the funnel 11ª.
The quantity of mercury at any time deposited from the electrode 8 maybe
known by observing the height to, which it rises as a liquid column in the tube 10,
and by a simple process of calculation based upon the. proportional part of the
current which passes through the shunt circuit and the known rate of decomposition
of the electrolyte, the amount of current which has passed through, the circuit can
be ascertained. The tabulated results of such, calculation which can be made with
ease by any skilled electrician, can be indicated; on a graduated scale applied to the
tube, so that the indication can be read by those unfamiliar with the electrical
art.
From time to time, as the results of the measurement are noted and recorded,
the metallic mercury can be drawn from the tube and poured back into the cell.
The measurement may also be taken by drawing off the mercury and weighing
it. The vessel in which the deposited mercury is caught may be charged with a
suitable liquid, the displacement of which by the mercury will indicate the. measure-
..ment. Instead of ascertaining the measurement of the meter by collecting the
deposited mercury in a receptacle and noting the increase thereof, the same result
may be attained by measuring at any time the loss of the body of metal forming
the anode, which can be contained in a graduated receptacle, or may be drawn off
and weighed.
The reason for employing a graphite pencil as the cathode is that it does not
amalgamate with the mercury, as metallic electrodes are apt to do, but it should be
understood that such electrode, though claimed specifically herein, does not form
an element of limitation of our invention broadly considered. Instead of dividing
the current by means of a constantly closed shunt circuit of definite resistance, so
that a part only shall pass through the electrolytic cell, the same result, may be
obtained by employing a switch controlling the shunt, with clock mechanism, which
at definite periods and for definite times will shunt the whole current from the main
circuit through the cell. This is shown in Figs. 4 and 5, in which B is a switch
comprising an annular metal disk divided by narrow strips of insulating material b
into a small segment 6' and a larger segment. 2. In the centre of this disk is a
metal plate 15 separated from the outer disk by insulating material 16. 17 is a
metal spring arm journaled in the plate 15, and having its end in travelling contact
with the disk, 2. This arm is rotated at a uniform,speed by clockwork 19, and
is electrically connected with one of the main electrical conductors. The segment b²
is connected by the conductor 2' with the lamps, and the segment 61 is connected
therewith by the conductors 4' and 5', forming a shunt in which is set the meter 6.
As the arm 17 rotates, so long as it is in contact with the segment 62, the current
passes through the arm and the conductor 2' directly to the lamps, but when it is in
contact with the segment b', (a definite proportion of its revolution) the current is
shunted through the meter.
The advantages of our invention, in respect of its simplicity and the facility
for measurement which it affords, will be appreciated by those skilled in the art.
We claim
1. In an electric meter. an electrolytic call containin
Maxouxial
14 and

page_text: having suitable electrodes, and a receptacle for catching the deposited mercury;
substantially as and for the purposes described.
2. In an electric meter, an electrolytical cell, containing a mercurial salt, and
having suitable electrodes, one of which is a body of metallic mercury, and a
receptacle for catching the deposited mercury; substantially as and for the purposes
described.
3. In an electric meter, an electrolytical cell, containing a mercurial salt, and
having suitable electrodes, of which the cathode is of carbon, and a receptacle for
catching the deposited mercury; substantially as and for the purposes described.
4. In an electric meter, an electrolytic cell, containing a mercurial salt, and
having suitable electrodes, and a glass receptacle for catching the deposited
mercury; substantially as and for the purposes described.
5. In an electric meter, an electrolytical cell, containing an electrolyte, and
having suitable electrodes, and a measuring receptacle for catching the deposited
cation; substantially as and for the purposes described.
6. In an electric meter, an electrolytic cell, containing a mercurial salt, and
having suitable electrodes, and a receptacle for the cation substantially as and for
the purposes described.
7. In an electric meter, an electrolytic cell, containing a mercurial salt, and
having suitable electrodes, one of which is a body of metallic mercury, and a
receptacle for the cation; substantially as and for the purposes described.
8. An electric meter constructed substantially as herein described and shown in
the drawings hereunto annexed.
9. In an electric meter an electrolytic cell containing a suitable salt solution,
and suitable electrodes, a receptacle for catching the deposited solid or liquid
which is graduated to read either the quantity of current or the price to be charged,
or both.
Dated this outh J CM 1900
EDWARDS & Co.,
35, Southampton Buildings, London, Agents for the Applicants.