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Chemical Effects Of Electric Current

Chemical Effects Of Electric Current
                                         GROUP PROJECT


                       1) ABOUT THE PROJECT
                       2) INTRODUCTION
                       3) DISCOVERY
                       4) ELECTROLYTIC CONDUCTION
                       5) MICHAEL FARADAY
                       6) WILLIAM NICHOLSON

                                           This project was started as part of the library junction project.

                               Chemicals have a lot of effect when they are tested with electrical objects. Here are some activity  and law's        of chemicals.


The fact that chemical changes produce electrical effect was discovered accidentally in 1971, by Luigi Galvani, an Italian professor. He found that an electric current flowed across two dissimilar metals. Volta, professor of natural philosophy successfully reproduced some of Galvani's results using inanimate things. The basic reason for electrochemical effects became clear rather slowly. Scientific investigations in this field actually began with the converse phenomenon namely chemical effects of electrical currents.


Electrolytes are substances that conduct electricity due to the drifting of ions. The positive ions are called cations, and the negative ions anions. The common examples of electrolytes are aqueous solutions of inorganic salts, acids and bases. Salts like NaCl, KCl are electrolytes in their molten state. Solutions of organic compounds are poor conductors. Solid state electrolytes (eg. AgI) with mobile ions are also present.

Here, we will see how aqueous solution of common salt conducts electricity. Solid crystalline NaCl is made up of Na+ and Cl- ions bound by a strong force of attraction. The energy required to separate Na+ and Cl- ions (i.e., dissociate them) is ~7.9eV per molecule. The thermal energy at room temperature, is only 0.03eV per molecule, and thus cannot dissociate NaCl. However, when NaCl is dissolved in water, the force of attraction is greatly reduced because of the high dielectric constant (= 81) of water. In fact, the force reduces by a factor of 81, and the thermal energy is sufficient to dissociate completely into Na+ and Cl- ions. This process is called ionisation.

Electrolyte conductivity is smaller than that of metals by a factor of 10-5 to 10-6 at room temperature. This is due to the smaller number density of ions as compared to free electrons, greater viscosity of the medium in which they move and the larger mass of ions.
Electrolysis is the dissociation of a electrolyte into ions at the electrodes by the passage of electric current.
That is, it is the conduction of electric current through an electrolyte together with the resulting chemical changes.

Electrolysis is carried out in an apparatus called voltameter or electrolytic cell. It consists of a glass vessel containing an electrolyte and 2 metal plates called electrodes, connected to a battery. The electrode connected to the positive terminal of the battery is called anode, and the one connected to the negative terminal is called cathode.

Electrolysis of Copper Sulphate solution

Electrolysis of copper sulphate

                       It is found that copper is removed from the anode and is deposited on the cathode. Due to ionization, the    CuSO4        
                       solution is dissociated.

                          Electrolysis of copper sulphate

When the source of emf is connected, a steady current flows in the circuit. Then, the following happen
1. Electrons flow from the negative terminal of the battery via the wire to the cathode C.

2. Electrode C is at a lower potential than electrode A. Therefore, the Cu2+ ions move towards C, while the  
 ions move towards


3. At the cathode C, the following reduction reaction occurs


These Cu atoms get deposited on the cathode.

4. At the anode A, the following oxidation reaction takes place. The Cu atoms are from the anode.

5. The Cu2+ ions go into the solution. The released electrons flow back to the positive terminal of the battery via the wire.
Thus, copper gets deposited at the cathode, while the anode loses an equivalent amount of copper. The concentration of CuSO4 in the solution remains unchanged.

Electrolysis of Silver Nitrate Solution

Here, the electrolyte is AgNO3 and the electrodes are silver plates. The process of electrolysis is identical to that of CuSO4 solution, except for one important difference. Copper has valency two, while silver has valency one. The reactions at the electrodes are:-

So, silver gets deposited at the cathode, while the anode loses an equal amount of Ag. The concentration of AgNO3 in the solution stays the same.
In the electrode position of silver, one electron circulated for depositing one silver atom on the cathode; but in the case of copper, two electrons circulate for the deposition of one copper atom


Michael Faraday, the great British experimental physicist, began his experiments on the passage of electricity through liquids, in 1834.


In 1834, Michael Faraday studied the passage of electricity through liquids. He called it electrolysis, as it was accompanied by the chemical decomposition of the electrolyte. The term ‘lysis’ in Greek means “setting free”. The metallic conductors through which the current enters and leaves the electrolyte are called electrodes. The electrode at high potential is called anode and the other at lower potential is called cathode. The passage of current through electrolytes was considered to take place through moving charged particles, which were called ‘ions’ by Faraday. The term ‘ion’ in Greek means a ‘wanderer’. The ion with negative charge is called ‘anion’ and the one with positive charge is called ‘cation’. 

Faraday's Laws of Electrolysis are:-

  • First law states that the mass of a substance deposited or liberated on an electrode during electrolysis is proportional to the total quantity of electric charge passed through the electrolyte.
  • Second law states that if same quantity of charge is passed through several electrolytes, the mass of substance deposited or liberated at electrodes is proportional to their chemical equivalent (equivalent weight)

            The Process of Electrolysis

The above statements are the conclusions made by Faraday after conducting a number of experiments on 'electrolysis'.

The process of electrolysis is carried out in an apparatus called voltameter.

If the electrolyte is a solution of copper sulphate (CuSO4) and the electrodes are copper plates, it is called a copper voltameter. On the other hand if the electrolyte is a solution of silver nitrate AgNO3 and electrodes are silver plates it is called a silver voltameter. When appropriate direct potential difference is applied across the electrodes, the electrolyte starts conducting current.

chemical equivalent

                                            Chemical Equivalent

Faraday's second law is illustrated in the figure where silver and copper voltameters are connected in series. For a given time, the same charge will pass through each voltameter. It will be seen that the masses of silver (Ag) and copper (Cu) deposited on the respective cathodes are in the ratio of 108:32. These values of 108 and 32 are called the chemical equivalents of silver and copper respectively.


The following figure shows a copper voltameter with copper electrodes. Current starts flowing in the circuit when the key is closed. Copper is removed from the anode and gets deposited on the cathode. The passage of current through the electrolyte is causing a chemical change. These chemical changes take place as long as current flows through the electrolyte. This process of electrolysis is utilised in many industrial and commercial applications. One of them is electroplating.


Electroplating is a process of depositing a thin layer of metal like gold or silver over an inferior material like iron. The object to be plated is used as a cathode. The metal to be deposited is used as an anode.

electroplating of silver

Electroplating of Silver

In the above figure, the metal to be deposited is silver and is used as anode. The object to be plated is used as  cathode. When the current flows through the electrolyte, the silver rod continuously dissolves into the solution and gets deposited on the object (key). 

Electrochemical Cells

A cell is a source of electricity in which chemical energy is converted into electrical energy. There are two types of cells called the primary and secondary cells A cell in which chemical reaction is not reversible is called a primary cell.

E.g., Daniel cell, Leclanche cell

            Daniel cell

Secondary cell is a cell in which chemical action is reversible. (e.g., lead acid accumulator, alkali accumulator).

Many chemical reactions take place and energy is released. If this happens in an electrolyte, with one or more of the ionic species in it as participants, it is then possible that the energy released directly and solely increases the electrical potential energy of the ions. The chemical reaction is thus a source of electrical energy. The system can be used as a source of electrical power if the chemical reaction proceeds at a steady rate. This is what one tries to achieve in an electrochemical cell.

Leclanche Cell


Leclanche cell of an outer glass vessel which is filled with saturated ammonium chloride (NH4Cl) solution. In it there stands a zinc rod and porous pot 'P' containing a carbon rod 'c' which is packed round with a mixture of manganese dioxide (MnO2) and powdered carbon.

wet leclanche cell

Wet Leclanche Cell

Therefore the carbon rod forms the positive pole and the zinc rod the negative pole. When the carbon rod and zinc rod are connected by a wire, the current flows from carbon to zinc through the wire.


Ammonium chloride, splits into ammonium and chloride ions. The chloride ions (Cl-) migrate to the zinc rod and deposit their negative charge at the zinc rod. Hence zinc becomes negatively charged and the reactions takes place in which zinc is converted to zinc chloride. The ammonium ions migrate to the carbon rod and make it positively charged. The hydrogen is then oxidised by MnO2 to form water and thus polarisation is prevented. Here Mn2O3 again changes to MnO2, by taking oxygen from the air.

The Dry Cell

The dry cell is a modification of the wet Leclanche cell in which the ammonium chloride solution is replaced with a jelly composed of starch, flour and ammonium chloride. The positive electrode, namely carbon rod is surrounded by a mixture of manganese dioxide and carbon. This is placed inside a zinc can which serves as the negative electrode.

The space between the central core and the zinc can is filled with the ammonium chloride jelly. The jelly is prevented from drying up by sealing the top of the cell with pitch. The carbon rod is prevented from coming in contact with the base of the zinc can, by a cardboard washer. The zinc can is also surrounded by an insulating thick paper covering. The working of the cell is similar to that of wet Leclanche cell.

dry leclanche cell

                   Dry Leclanche Cell

The emf of this cell is about 1.5V. It is portable and used in torches, transistors etc.

Electrochemical and Chemical Equivalents

Substance Electro chemical equivalent, Z(kg/C) Atomic mass (u) Valency, p Chemical equivalent, E(g/mol)
Hydrogen 1.045x10 - 8 1.008 1 1.008
Copper 3.249x10 - 7 63.57 2 31.78
Silver 1.118x10 - 6
107.88 1 107.88
Zinc 3.387x10 - 7
65.39 2 32.695
Chromium 1.800x10 - 7
51.996 3 17.332
Aluminium 9.360x10 - 8 27.1 3 9.03
Gold 6.812x10 - 7
197.2 3 65.73
Nickel 3.040x10 - 7
58.68 2 29.34
Oxygen 8.238x10 - 8 16 2 8
Chlorine 3.671x10 - 7
35.46 1 35.46

where F(=NAe) is a fundamental constant and is called Faraday's constant. Its value is 96487 C mol-1.

Faraday's constant is equal to the amount of charge required to liberate the mass of a substance during electrolysis equal to its chemical equivalent (in gm).

Equation (1) is the combined form of Faraday's laws of electrolysis.

For a given electrolyte,

Faraday's laws have a lot of significance. They imply that to liberate one atom of a substance, the charge required is That is, the charge per ion of any substance is Two important results follow from this:

(i)  The chemical concept of valency is related to electric charge.

(ii) Since p is an integer, all charges are multiples of an elementary charge


The quantitative significance is that the value of e can be calculated by using values of F from electrolysis experiments. The value of e comes out to be ~1.6 x 10-19 C.

Applications of Electrolysis

The phenomenon of electrolysis has many scientific and commercial applications.


Electroplating of objects by nickel, silver and gold is very common. The conducting material to be electroplated is made the cathode of an electrolytic cell. A strip of metal whose coating is required on the cathode material is used as the anode, while a soluble salt of the same anode material is taken as the electrolyte. Below figure shows an experimental set-up used for electroplating. When the current is passed through the circuit, a thin film of the metal deposits on the cathode. To make the electroplating uniform and firmly adherent, a suitable current strength is used. If the current strength is very high, the plating may become brittle. For gold plating, we need a current from 1V to 3V batteries; and for copper, current is drawn from a battery of 5V to 10V.

Electroplating of objects by nickel, silver and gold

Extraction of metals from ores

Certain metals are extracted from their ores using electrolysis. For example, aluminium is obtained by passing an electric current through fused bauxite (Al2O3) and cryolite (Na3AlF6). Active metals like sodium, calcium and magnesium are also extracted from their ores using electrolysis.

Purification of Metals

For this purpose, the impure metal is made the anode, and a pure metallic strip is used as cathode. A soluble salt of pure metal is taken as the electrolyte. On passing current, the impure metal anode dissolves but only the pure metal deposits on the cathode. Many metals like copper are purified up to 99.99% using electrolysis.

Electrolytic Capacitors

These capacitors consist of two aluminium electrodes placed in an electrolytic mixture of ammonium borate for sodium phosphate in glycerine. When a steady current is passed, a thin layer of dielectric aluminium oxide (or hydroxide) is formed on the anode. Such very thin films can offer large values of capacitance. Modern capacitors use electrolytes in the form of a paste or a solution soaked in paper placed between two aluminium foils. If the potential across the two electrodes becomes excessively high, this dielectric layer breaks down and temporarily ceases to function. However, it is possible to regenerate this layer and repair the damage. Such capacitors are very common in power circuits.

MICHAEL FARADAY: A brief Biography

Faraday was a British chemist and physicist who contributed significantly to the study of electromagnetism and electrochemistry.

Michael Faraday was born on 22 September 1791 in south London. His family was not well off and Faraday received only a basic formal education. When he was 14, he was apprenticed to a local bookbinder and during the next seven years, educated himself by reading books on a wide range of scientific subjects. In 1812, Faraday attended four lectures given by the chemist Humphry Davy at the Royal Institution. Faraday subsequently wrote to Davy asking for a job as his assistant. Davy turned him down but in 1813 appointed him to the job of chemical assistant at the Royal Institution.

A year later, Faraday was invited to accompany Davy and his wife on an 18 month European tour, taking in France, Switzerland, Italy and Belgium and meeting many influential scientists. On their return in 1815, Faraday continued to work at the Royal Institution, helping with experiments for Davy and other scientists. In 1821 he published his work on electromagnetic rotation (the principle behind the electric motor). He was able to carry out little further research in the 1820s, busy as he was with other projects. In 1826, he founded the Royal Institution's Friday Evening Discourses and in the same year the Christmas Lectures, both of which continue to this day. He himself gave many lectures, establishing his reputation as the outstanding scientific lecturer of his time.

In 1831, Faraday discovered electromagnetic induction, the principle behind the electric transformer and generator. This discovery was crucial in allowing electricity to be transformed from a curiosity into a powerful new technology. During the remainder of the decade he worked on developing his ideas about electricity. He was partly responsible for coining many familiar words including 'electrode', 'cathode' and 'ion'. Faraday's scientific knowledge was harnessed for practical use through various official appointments, including scientific adviser to Trinity House (1836-1865) and Professor of Chemistry at the Royal Military Academy in Woolwich (1830-1851).

However, in the early 1840s, Faraday's health began to deteriorate and he did less research. He died on 25 August 1867 at Hampton Court, where he had been given official lodgings in recognition of his contribution to science. He gave his name to the 'farad', originally describing a unit of electrical charge but later a unit of electrical capacitance.

See the video on Michael Faraday in the "Videos" section

More About Electroplating

Electroplating is a plating process in which metal ions in a solution are moved by an electric field to coat an electrode. The process uses electrical current to reduce cations of a desired material from a solution and coat a conductive object with a thin layer of the material, such as a metal. Electroplating is primarily used for depositing a layer of material to bestow a desired property (e.g., abrasion and wear resistance, corrosion protection, lubricity, aesthetic qualities, etc.) to a surface that otherwise lacks that property. Another application uses electroplating to build up thickness on undersized parts.

The process used in electroplating is called electrodeposition. It is analogous to a galvanic cell acting in reverse. The part to be plated is the cathode of the circuit. In one technique, the anode is made of the metal to be plated on the part. Both components are immersed in a solution called an electrolyte containing one or more dissolved metal salts as well as other ions that permit the flow of electricity. A power supply supplies a direct current to the anode, oxidizing the metal atoms that comprise it and allowing them to dissolve in the solution. At the cathode, the dissolved metal ions in the electrolyte solution are reduced at the interface between the solution and the cathode, such that they "plate out" onto the cathode. The rate at which the anode is dissolved is equal to the rate at which the cathode is plated, vis-a-vis the current flowing through the circuit. In this manner, the ions in the electrolyte bath are continuously replenished by the anode.

Other electroplating processes may use a nonconsumable anode such as lead. In these techniques, ions of the metal to be plated must be periodically replenished in the bath as they are drawn out of the solution.


Electroplating of a metal (Me)              with copper in a copper sulfate bath.

The anode and cathode in the electroplating cell are both connected to an external supply of direct current - a battery or, more commonly, a rectifier. The anode is connected to the positive terminal of the supply, and the cathode (article to be plated) is connected to the negative terminal. When the external power supply is switched on, the metal at the anode is oxidized from the zero valence state to form cations with a positive charge. These cations associate with the anions in the solution. The cations are reduced at the cathode to deposit in the metallic, zero valence state. For example, in an acid solution, copper is oxidized at the anode to Cu2+ by losing two electrons. The Cu2+ associates with the anion SO42- in the solution to form copper sulfate. At the cathode, the Cu2+ is reduced to metallic copper by gaining two electrons. The result is the effective transfer of copper from the anode source to a plate covering the cathode.

The plating is most commonly a single metallic element, not an alloy. However, some alloys can be electrodeposited, notably brass and solder.

Many plating baths include cyanides of other metals (e.g., potassium cyanide) in addition to cyanides of the metal to be deposited. These free cyanides facilitate anode corrosion, help to maintain a constant metal ion level and contribute to conductivity. Additionally, non-metal chemicals such as carbonates and phosphates may be added to increase conductivity.

When plating is not desired on certain areas of the substrate, stop-offs are applied to prevent the bath from coming in contact with the substrate. Typical stop-offs include tape, foil, lacquers, and waxes.


Initially, a special plating deposit called a "strike" or "flash" may be used to form a very thin (typically less than 0.1 micrometer thick) plating with high quality and good adherence to the substrate. This serves as a foundation for subsequent plating processes. A strike uses a high current density and a bath with a low ion concentration. The process is slow, so more efficient plating processes are used once the desired strike thickness is obtained.

The striking method is also used in combination with the plating of different metals. If it is desirable to plate one type of deposit onto a metal to improve corrosion resistance but this metal has inherently poor adhesion to the substrate, a strike can be first deposited that is compatible with both. One example of this situation is the poor adhesion of electrolytic nickel on zinc alloys, in which case a copper strike is used, which has good adherence to both.

 Current density

A timecourse of electroplating with      copper. The anode on the left is pure copper, the safety pin on the right is the target for plating. The first image is before the electrical supply has been connected, the second image shows plating with a thin layer of copper and the later images show the buildup of "fluffy" structurally weak deposits.

The current density (current of the electroplating current divided by the surface area of the part) in this process strongly influences the deposition rate, plating adherence, and plating quality. This density can vary over the surface of a part, as outside surfaces will tend to have a higher current density than inside surfaces (e.g., holes, bores, etc.). The higher the current density, the faster the deposition rate will be, although there is a practical limit enforced by poor adhesion and plating quality when the deposition rate is too high.

While most plating cells use a continuous direct current, some employ a cycle of 8–15 seconds on followed by 1–3 seconds off. This technique is commonly referred to as "pulse plating" and allows high current densities to be used while still producing a quality deposit. In order to deal with the uneven plating rates that result from high current densities, the current is even sometimes reversed in a method known as "pulse-reverse plating", causing some of the plating from the thicker sections to re-enter the solution. In effect, this allows the "valleys" to be filled without over-plating the "peaks". This is common on rough parts or when a bright finish is required. In a typical pulse reverse operation, the reverse current density is three times greater than the forward current density and the reverse pulse width is less than one-quarter the forward pulse width. Pulse-reverse processes can be operated at a wide range of frequencies from several hundred hertz up to the order of megahertz.

Brush electroplating

A closely-related process is brush electroplating, in which localized areas or entire items are plated using a brush saturated with plating solution. The brush, typically a stainless steel body wrapped with a cloth material that both holds the plating solution and prevents direct contact with the item being plated, is connected to the positive side of a low voltage direct-current power source, and the item to be plated connected to the negative. The operator dips the brush in plating solution then applies it to the item, moving the brush continually to get an even distribution of the plating material. The brush acts as the anode, but typically does not contribute any plating material, although sometimes the brush is made from or contains the plating material in order to extend the life of the plating solution.

Brush electroplating has several advantages over tank plating, including portability, ability to plate items that for some reason cannot be tank plated (one application was the plating of portions of very large decorative support columns in a building restoration), low or no masking requirements, and comparatively low plating solution volume requirements. Disadvantages compared to tank plating can include greater operator involvement (tank plating can frequently be done with minimal attention), and inability to achieve as great a plate thickness.

 Electroless deposition

Usually an electrolytic cell (consisting of two electrodes, electrolyte, and external source of current) is used for electrodeposition. In contrast, an electroless deposition process uses only one electrode and no external source of electric current. However, the solution for the electroless process needs to contain a reducing agent so that the electrode reaction has the form:

M^{z+} + Red_{solution} stackrel{text{catalytic surface}} Longrightarrow M_{solid} + Oxy_{solution}

In principle any water-based reducer can be used although the redox potential of the reducer half-cell must be high enough to overcome the energy barriers inherent in liquid chemistry. Electroless nickel plating uses hypophosphite as the reducer while plating of other metals like silver, gold and copper typically use low molecular weight aldehydes.

A major benefit of this approach over electroplating is that power sources and plating baths are not needed, reducing the cost of production. The technique can also plate diverse shapes and types of surface. The downside is that the plating process is usually slower and cannot create such thick plates of metal. As a consequence of these characteristics, electroless deposition is quite common in the decorative arts.


Cleanliness is essential to successful electroplating, since molecular layers of oil can prevent adhesion of the coating. ASTM B322 is a standard guide for cleaning metals prior to electroplating. Cleaning processes include solvent cleaning, hot alkaline detergent cleaning, electrocleaning, and acid etc. The most common industrial test for cleanliness is the waterbreak test, in which the surface is thoroughly rinsed and held vertical. Hydrophobic contaminants such as oils cause the water to bead and break up, allowing the water to drain rapidly. Perfectly clean metal surfaces are hydrophilic and will retain an unbroken sheet of water that does not bead up or drain off. ASTM F22 describes a version of this test. This test does not detect hydrophilic contaminants, but the electroplating process can displace these easily since the solutions are water-based. Surfactants such as soap reduce the sensitivity of the test and must be thoroughly rinsed off.


Electroplating changes the chemical, physical, and mechanical properties of the workpiece. An example of a chemical change is when nickel plating improves corrosion resistance. An example of a physical change is a change in the outward appearance. An example of a mechanical change is a change in tensile strength or surface hardness.


Obtaining a uniform thickness with electroplating can be difficult depending on the geometry of the object being plated. The plating metal is preferentially attracted to external corners and protrusions, but unattracted to internal corners and recesses. These difficulties can be overcome with multiple anodes or a specially shaped anode that mimics the object geometry, however both of these solutions increase cost. The ability of a plating to cover uniformly is called throwing power; the better the "throwing power" the more uniform the coating.

One cannot electroplate chrome or silver on any given substrate directly. Many plating processes require an intermediate plating step. For example, when chrome plating carbon steel, one would need to electroplate copper on top of carbon steel, followed by nickel and then chrome to get uniform chrome plated part. These additional steps add considerably to the cost and time to electroplate. Thicker coatings require similar multilayer structures. A hard chrome coating would require multiple alternating coatings of copper and chrome.


Nickel plating

Although it is not confirmed, the Parthian Battery may have been the first system used for electroplating.

Modern electrochemistry was invented by Italian chemist Luigi V. Brugnatelli in 1805. Brugnatelli used his colleague Alessandro Volta's invention of five years earlier, the voltaic pile, to facilitate the first electrodeposition. Brugnatelli's inventions were suppressed by the French Academy of Sciences and did not become used in general industry for the following thirty years.

By 1839, scientists in Britain and Russia had independently devised metal deposition processes similar to Brugnatelli's for the copper electroplating of printing press plates. Soon after, John Wright of Birmingham, England discovered that potassium cyanide was a suitable electrolyte for gold and silver electroplating. Wright's associates, George Elkington and Henry Elkington were awarded the first patents for electroplating in 1840. These two then founded the electroplating industry in Birmingham from where it spread around the world.

The Norddeutsche Affinerie in Hamburg was the first modern electroplating plant starting its production in 1876.

As the science of electrochemistry grew, its relationship to the electroplating process became understood and other types of non-decorative metal electroplating processes were developed. Commercial electroplating of nickel, brass, tin, and zinc were developed by the 1850s. Electroplating baths and equipment based on the patents of the Elkingtons were scaled up to accommodate the plating of numerous large scale objects and for specific manufacturing and engineering applications.

The plating industry received a big boost from the advent of the development of electric generators in the late 19th century. With the higher currents, available metal machine components, hardware, and automotive parts requiring corrosion protection and enhanced wear properties, along with better appearance, could be processed in bulk.

The two World Wars and the growing aviation industry gave impetus to further developments and refinements including such processes as hard chromium plating, bronze alloy plating, sulfamate nickel plating, along with numerous other plating processes. Plating equipment evolved from manually operated tar-lined wooden tanks to automated equipment, capable of processing thousands of kilograms per hour of parts.

One of the American physicist Richard Feynman's first projects was to develop technology for electroplating metal onto plastic. Feynman developed the original idea of his friend into a successful invention, allowing his employer (and friend) to keep commercial promises he had made but could not have fulfilled otherwise

William Nicholson
In 1800, a British chemist, William Nicholson (1753-1815), had shown that if electrodes were immersed in water, and a current was passed, bubbles of oxygen and hydrogen were produced. Oxygen bubbles formed on the electrode connected to the   positive terminal of the battery and hydrogen bubbles formed on the other electrode.

About William Nicholson

William Nicholson (13 December 1753 – 21 May 1815) was a renowned English chemist and writer on "natural philosophy" and chemistry, as well as a translator, journalist, publisher, scientist, and inventor.

The year of Nicholson's birth in London has been recorded but, as was common in the 18th century, the day and month remained undocumented. He was the son a solicitor from London, who practiced in the Inner Temple. After leaving school, he made two voyages as a midshipman in the service of the British East India Company. Subsequently, he briefly embarked upon a law practice but, having become acquainted with Josiah Wedgwood in 1775, he moved to Amsterdam, where he made a living for a few years as agent for the sale of pottery.

On his return to England he was persuaded by Thomas Holcroft to apply his writing talents to the composition of light literature for periodicals, while also assisting Holcroft with some of his plays and novels. Meanwhile he devoted himself to the preparation of An Introduction to Natural Philosophy, which was published in 1781 and was at once successful. A translation of Voltaire's Elements of the Newtonian Philosophy soon followed, and he then entirely devoted himself to scientific pursuits and philosophical journalism. In 1784 he was appointed secretary to the General Chamber of Manufacturers of Great Britain, and he was also connected with the Society for the Encouragement of Naval Architecture, established in 1791. He gave much attention to the construction of various machines for comb-cutting, file-making, cylinder printing and other uses—he also invented an areometer.

In 1797 he began to publish and contribute to the Journal of Natural Philosophy, Chemistry and the Arts, generally known as Nicholson's Journal, the earliest work of its kind in Great Britain— the publication continued until 1814. The journal included the first comprehensive descriptions of aerodynamics with George Cayley's "On Aerial Navigation", which inspired the Wright brothers a hundred years later.

In 1799 he established a school in London's Soho Square, where he taught natural philosophy and chemistry.

In 1800 he and Anthony Carlisle discovered electrolysis, the decomposition of water into hydrogen and oxygen by voltaic current.

Besides considerable contributions to the Philosophical Transactions, Nicholson wrote translations of Fourcroy's Chemistry (1787) and Chaptal's Chemistry (1788), First Principles of Chemistry (1788) and a Chemical Dictionary (1795); he also edited the British Encyclopaedia, or Dictionary of Arts and Sciences (6 vols., London, 1809). He also wrote an autobiography which was extant in manuscript at the end of the 19th century, but has since been presumed lost.

During the later years of his life, Nicholson's attention was chiefly directed to water supply engineering at Portsmouth, at Gosport and in Southwark. William Nicholson died in Bloomsbury at the age of 61 on 21 May 1815.

Links from which the sources were adapted:

1)  www.tutorvista.com/content/physics/physics-iv/thermal-chemical-currents/chemical-effects-current.php

2)  http://en.wikipedia.org/wiki/Michael_Faraday

3) http://en.wikipedia.org/wiki/William_Nicholson_(chemist)