US4548679A
Expired / Lapsed
US
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Hanging mercury drop electrode capable of automatic control
Assignee: Consiglio Nazionale delle Richerche
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Filing: 1983-11-29
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Granted: 1985-10-22
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Expires: 2003-11-29
Abstract
Abstract A hanging mercury drop electrode is described which makes use of a capillary tube with an inverted-U shape, removably fastened to an air-tight pressure-resistant cylindrical mercury reservoir. The capillary tube has a sufficiently thin inner diameter (0.35×10 -2 to 0.5×10 -2 cm) and a sufficient length (40 to 50 cm) such that the viscous forces prevent mercury from flowing through the capillary tube, once a height of the mercury head is selected (1 to 2 cm) which roughly counterbalances the back-pressure acting on the drop surface. To increase the drop size, a pressure higher than the atmospheric pressure is transmitted to the mercury reservoir from a pressure generator via an electromechanical valve, which is controlled by a timer or a microprocessor. The drop becomes stationary as soon as the mercury reservoir is connected with the outer atmosphere via another electromechanical valve. A whole cycle of operations of the present electrode comprises: (1) detachment of a preformed drop by a hammer which knocks the capillary tube; (2) growth of a new drop by application of a pressure higher than the atmospheric pressure to the mercury reservoir; (3) blockage of the drop area by application of the atmospheric pressure to the mercury reservoir; (4) desired electroanalytical measurement on the resulting static mercury drop.
Inventors
- 👤 Rolando Guidelli
- 👤 Maria L. Foresti
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 02:37
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/26; G01N27/28; G01N27/30; G01N27/34
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
150 words
A dropping mercury electrode which operates with a drop of mercury which comprises a holding mercury reservoir, a first capillary tube of inverted U-shape, one end of the tube being free, said mercury drop being formed on said free end, the other end being dipped in said mercury reservoir, said capillary tube being of a sufficiently small length and of a sufficiently small inner diameter and the level of said free end being held at a constant and sufficiently small difference below the upper level of the mercury in said reservoir that viscous forces prevent mercury from flowing through said capillary tube when said capillary end holding said capillary drop and said reservoir are both subject to the same atmospheric pressure and wherein said first capillary tube of inverted U-shape has an internal diameter between 0.35×10 2 and 0.5×10 -2 cm and has a length of 40 to 50 cm.
Claim 2
Dependent Claim
150 words
A dropping mercury electrode which operates with a drop of mercury which comprises a holding mercury reservoir, a first capillary tube of inverted U-shape, one end of the tube being free, said mercury drop being formed on said free end, the other end being dipped in said mercury reservoir, said capillary tube being of a sufficiently small length and of a sufficiently small inner diameter and the level of said free end being held at a constant and sufficiently small difference below the upper level of the mercury in said reservoir that viscous forces prevent mercury from flowing through said capillary tube when said capillary end holding said capillary drop and said reservoir are both subject to the same atmospheric pressure and wherein said first capillary tube of inverted U-shape has an internal diameter between 0.35×10 2 and 0.5×10 -2 cm and has a length of 40 to 50 cm.
Claim 3
Dependent Claim
34 words
The electrode according to claim 1 which is provided with a system of electrovalves, said electrovalves being used to apply and discontinue pressure exerted by an inert gas on the mercury in said reservoir.
Claim 4
Dependent Claim
68 words
The electrode according to claim 2 wherein said inert gas is nitrogen, compressed air or another inert gas which is applied from a cylinder and the cylinder is provided with means for reducing the pressure and for adjusting the pressure between 3 and 12 atmospheres and the drop of mercury is blocked by restoring the atmospheric pressure by establishing communication between said mercury reservoir and the external environment.
Claim 5
Dependent Claim
30 words
The electrode according to claim 1 wherein the free end of said first capillary tube is at a level lower with respect to the mercury reservoir of about 1-1.5 cm.
Claim 6
Dependent Claim
32 words
The electrode according to claim 1 wherein a second capillary tube of greater internal diameter is soldered to said first capillary tube of internal diameter between 0.35×10 2 and 0.5×10 -2 cm.
Claim 7
Dependent Claim
33 words
The electrode according to claim 5 wherein said first capillary is connected to said second capillary and a platinum wire is directly soldered to the connection point between said first and second capillary.
Claim 8
Independent Claim
193 words
A method of rapidly generating static mercury drops of reproducible size and of holding them for an indefinitely long time at one end of a capillary tube immersed in a solution subject to the atmospheric pressure, the other end of said capillary tube being connected to a mercury reservoir, which method comprises: (a) setting the level of said capillary end holding said mercury drop lower than the upper level of the mercury pool in said reservoir by about 1 to 2 cm, so as to roughly counterbalance the back-pressure; (b) choosing said capillary tube of a sufficient length and of a sufficiently small inner diameter such that, in conjunction with said difference in level, viscous forces prevent mercury from flowing through said capillary tube when said mercury reservoir is subject to the atmospheric pressure; (c) causing the mercury to flow through said capillary tube and hence said mercury drop to grow by application of a pressure higher than the atmospheric pressure to said mercury reservoir; (d) limiting the surface area of said mercury drop after attainment of the desired size by rapidly switching the pressure on said mercury reservoir to the atmospheric value.
Claim 9
Independent Claim
193 words
A method of rapidly generating static mercury drops of reproducible size and of holding them for an indefinitely long time at one end of a capillary tube immersed in a solution subject to the atmospheric pressure, the other end of said capillary tube being connected to a mercury reservoir, which method comprises: (a) setting the level of said capillary end holding said mercury drop lower than the upper level of the mercury pool in said reservoir by about 1 to 2 cm, so as to roughly counterbalance the back-pressure; (b) choosing said capillary tube of a sufficient length and of a sufficiently small inner diameter such that, in conjunction with said difference in level, viscous forces prevent mercury from flowing through said capillary tube when said mercury reservoir is subject to the atmospheric pressure; (c) causing the mercury to flow through said capillary tube and hence said mercury drop to grow by application of a pressure higher than the atmospheric pressure to said mercury reservoir; (d) limiting the surface area of said mercury drop after attainment of the desired size by rapidly switching the pressure on said mercury reservoir to the atmospheric value.
Claim 10
Dependent Claim
123 words
A method of periodically generating static mercury drops of reproducible size which comprises using the method defined in claim 7 and further comprising the following steps: (a) dislodging of a static drop by imparting to said capillary tube a mechanical shock; (b) forming of a new drop by connecting said mercury reservoir for a predetermined period of time to a pressure generator so as to subject said reservoir to said pressure higher than the atmospheric pressure and to cause the growth of said new drop; (c) limiting the surface area of said new drop by connecting said mercury reservoir with the outer atmosphere; (d) using said new static drop for any desidered electrochemical or electroanalytical measurements; and (e) repetition of the steps (a)-(d).
Claim 11
Dependent Claim
19 words
The method recited in claim 8 wherein the various steps are performed under the control of an electronic timer.
Claim 12
Dependent Claim
18 words
The method recited in claim 8 wherein the various steps are performed under the control of a microprocessor.
Claim 13
Dependent Claim
58 words
The method recited in claim 8, wherein said mercury reservoir, made of some pressure-resistant material inert to mercury, is connected with a pressure generator consisting of a cylinder of an inert gas via a pressure reducer and an electromechanical valve during said step (b), and is connected with the outer atmosphere via another electromechanical valve during step (c).
Claim 14
Dependent Claim
43 words
The method recited in claim 7, wherein said capillary has an inverted U-shape, a length between 40 and 50 cm, an inner diameter between 0.35×10 -2 and 0.5×10 -2 cm and is held fast to said mercury reservoir by a suitable fastening device.
Claim 15
Dependent Claim
62 words
The method recited in claim 12, wherein the inner diameter at the end of said U-shaped capillary which holds said hanging mercury drop, and hence the maximum diameter of said mercury drop, are made larger by soldering to said capillary tube of inner diameter between 0.35×10 -2 and 0.5×10 -2 cm, a segment of a second capillary tube of larger inner diameter.
Claim 16
Dependent Claim
38 words
The method recited in claim 13, wherein electrical connection with said mercury drop is made by means of a platinum wire which is directly soldered to the connection between the two said capillary tubes of different inner diameter.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-10-21 | 1989-04-22 | 1989-10-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-10-21 | 1993-04-22 | 1993-10-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-10-21 | 1997-04-22 | 1997-10-22 | $7700.00 | Window Closed / Lapsed |