Improvements in Voltameters.
Year: 1893

page_text: Date of Application, 15th Nov., 1893-Accepted, 20th Jan., 1894
Improvements in Voltameters.
I, HENRI ADRIEN NABER, Phil. Cand., of 30, Regulirsgracht, Amsterdam, in
the Kingdom of Holland, 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 a voltameter, in which the graduated tube or burette
which serves for the reception of the gases is divided into two parts viz., an under
part which surrounds the electrodes, and an upper part which collects the gas,
so that by shifting or turning one part upon the other, the reception of the gas
may be commenced at a given time, and when the desired period of action has
expired can be interrupted, without its being necessary to switch the voltameter
out of the circuit.
The voltameter which embodies the above points is further provided with an
arrangement which allows of its being easily filled and of the level of the fluid
in the outer part being lowered to that of the fluid in the burette, as is necessary
for the exact reading off of the quantity of gas collected.
To enable my invention to be fully understood will describe the same by
reference to the accompanying drawing which represents a voltameter having the
lower part, which is separate from the burette proper, composed of two caps or
hoods, one of which is arranged over one electrode and the other over the other
electrode, and in the said drawing,
Figure 1 is a vertical section.
Figure 2 is a cross section on the line a-b of Figure 1.
Figure 3 is a cross section on the line c-d of Figure 1, and,
Figure 4 is a plan, the cover which closes the voltameter being supposed to be
removed.
The outer glass vessel 1, 2, 3, which surrounds the electrodes and the burette,
consists of a lower wide cylinder 1 and a narrower upper one 2 which joins on to the
cylinder 1, the upper end 3 of the cylinder 2 being widened out like a beaker, and
closed by a cover which is not air-tight when closed.
The vessel is closed below by a removable false bottom 4, consisting of glass,
gutta-percha or other material, which forms a stopper, and is jointed air-tight to
the lower edge of the cylinder 1 by some easily removable cement, such as wax.
The cylinder 1 surrounds a receiver 5, made of glass, gutta-percha or the like,
from the lid of which a glass tube 6 passes outwards through the cylinder 1, this
tube being connected by an india rubber tube 7 with two india-rubber balls 8
which serve as bellows. Above the balls a branch 9 passes off from the tube, the
free end of which branch can be closed by means of a pinchcock 10. Just above
the bottom of the receiver 5 there is a lateral aperture 11, from which a tube 12
passes upwards to a point above the lid of the receiver 5.
The receiver 5 is filled with dilute sulphuric acid. By pressure upon the lower
of the india-rubber balls, air is forced into the receiver 5, and the, fluid which it
contains is thereby forced through the tube 12 into the vessel 1, 2. If on the
contrary the pinchcock 10 on the branch 9 be opened, the air escapes from the
receiver ō and the fluid returns into the receiver.
On one side of the receiver 5 (in Figures 1 and 2 the right) the conducting
wires 14 enter through branches 13 from the cylinder 1, each of which wires ends
in an annular platinum electrode 15. Over each of these electrodes a cylindrical

page_text: hood 16 is inverted, the said hood being supported below by its respective wire 14
and lying laterally against the wall of the receiver 5. At its upper end is a
beak 17, which has an opening 18 of about 4 mm diameter. One or two india
rubber bands 19, are placed around the two hoods to hold them together and
prevent them from shifting.
The burette 20 is set in the vessel 1, 2, 3 above the receiver 5, in such a way
that it can be turned on its axis. It is surrounded by a cylinder 21, which is open
at the top but is fitted tightly to the burette at the bottom. The cylinder 21
contains the same fluid, as the receiver 5. A thermometer 22 dips into this fluid,
and is suspended on the upper edge of the cylinder by means of a wire. The
cylinder 21 terminates at the upper end in a flat glass lug, which serves as a handle,
by means of which the cylinder, together with the burette, may be conveniently
turned, lifted out, and inserted. The said cylinder 21 is further provided outside
with an india-rubber ring 24, 25 at the ends, these rings serving to centre the
burette. The upper ring 25 may be of such size as to rest on the cylinder 2 and
thus support the burette; in which case it is furnished with slots on its outer edge,
so as to allow of the exit of air. The burette may, however, be supported by its
Tower end resting upon the top of the receiver 5, which is in this case curved
upward. The lower, open, end of the burette is curved out laterally, and is so
widened (see the plan Figure 2) that it is situated in the position shewn in dotted
lines in the drawing (Figures 1 and 2) above the openings 18 of the hoods 16
which surround the electrodes 15, and catches the gas which escapes through the
latter. The burette may also be so arranged that its lower end only covers the
opening 18 of one of the two hoods 16, or the other, if it be only desired to catch
the oxygen or hydrogen. In the annular space between the cylinders 21 and 2 a
hydrometer 26 may be introduced if thought desirable.
The method of using the voltameter above described is as follows :—
The burette is placed in the position shewn by full lines in Figure 1, and the
cock 27 with which the upper part of the burette is furnished is opened. The
lower india-rubber ball 8 is then compressed, and the fluid thereby driven out of
the receiver 5 into the vessel 1, 2, 3, until the latter and the burette are filled up
to the zero point of the latter. The cock of the burette is then closed and the
electric current is sent through the electrodes. As soon as the current is constant,
the burette is turned into such a position that its lower end catches the gas which
escapes from one or the other of the electrodes 15. After the lapse of a given time
the burette is turned into the initial position without interrupting the current. The
pinchcock 10 is then opened and kept so until the surface of the outer annular
column of fluid, which occupies the space between the cylinders 21 and 2, stands at
the same height as the fluid in the burette, that is to say, until the pressure of the
gas in the burette is equal to that of the atmosphere. If the column of water
outside has been run down too low, it is elevated again to the required height by
the use of the india rubber balls. The pinchcock is then closed, the temperature
and the height of the barometer read off, and the strength of the current calculated
by the help of a table, which is preferably etched outside in the lower part of the
vessel 1, 2, 3.
The volume of the gas collected is read off in cubic centimetres, the time
expressed in seconds, and that number selected from the table which corresponds to
the height of the barometer and the temperature.
The volume divided by the product of the time and the number in the table
yields a quotient which is the mean strength of the current. If the quantity
of electricity is to be determined, the volume is divided by the number in the
table.
It is best to insert a glass rod 28, Figures 1, 3 and 4, between the burette and
the cylinder 21 which surrounds the latter, the lower end of this rod being bent off
laterally and curved so that by means of the said rod the fluid for the burette may
be stirred before each determination, so that it may be of homogeneous density and
of an equable temperature.

page_text: The gas evolved can never drive the fluid out of contact with the electrodes,
since, if the burette be intentionally filled quite full of gas, the gas thereafter
evolved passes round the lower edge of the burette into the vessel 1, 2, 3, and
rises in the latter.
The burette can be taken out at any time, even though the current be not inter-
rupted, so that the burette can be easily cleaned, or replaced by another one, larger
or smaller.
The gas collected in the burette can be conducted, after the cock of the burette
is opened, through a tube attached to the latter, into a separate receiver, and there
be stored.
The voltameter can also be employed for ordinary volumetric purposes.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:-
1. A voltameter, in which the graduated tube or burette which is used for the
collection of the gas is divided into two parts viz. :-a lower part which surrounds
the electrodes (and may if desired consist of hoods or caps) and an upper part
which collects the gas, so that by shifting or turning the one part upon the other,
the collection of the gas may be begun at a given time, and stopped when such time
has expired, without its being necessary to switch the voltameter out of the circuit,
substantially as described.
2. A voltameter of the kind indicated in Claim 1, the outer vessel (1, 2, 3) of
which communicates with a receiver (5) containing the fluid to be electrolysed, in
such a way that by forcing air or gas into the holder, fluid is driven out of the latter
into the burette, and when the pressure is removed the fluid returns into the
receiver, so that the ejection and return of the fluid may be so controlled that the
fluid within the burette and outside it may take up the position desired, substan-
tially as described.
3. The manufacture and use of the improved voltameter hereinbefore described
and illustrated in the accompanying drawing.
Dated the 15th day of November 1893.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.