Feb 182016
 

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Today is the birthday (1745) of Alessandro Giuseppe Antonio Anastasio Volta an Italian physicist and chemist, who is credited as the inventor of the electrical battery and the discoverer of methane. Volta was born in Como, a town in present-day northern Italy (near the Swiss border). In 1794, Volta married an aristocratic woman, also from Como, Teresa Peregrini, with whom he raised three sons: Zanino, Flaminio, and Luigi. His own father Filippo Volta was of noble lineage. His mother Donna Maddalena came from the family of the Inzaghis.

In 1774, he became a professor of physics at the Royal School in Como. A year later, he improved and popularized the electrophorus, a device that produced static electricity. His promotion of it was so extensive that he is often credited with its invention, even though a machine operating on the same principle was described in 1762 by the Swedish experimenter Johan Wilcke. In 1777, he traveled through Switzerland. There he befriended H. B. de Saussure.

In the years between 1776 and 1778, Volta studied the chemistry of gases. He researched and discovered methane after reading a paper by Benjamin Franklin on “flammable air”. In November 1776, he found methane at Lake Maggiore, and by 1778 he managed to isolate the gas. He devised experiments such as the ignition of methane by an electric spark in a closed vessel.

Volta also studied what we now call electrical capacitance, developing separate means to study both electrical potential (V ) and charge (Q ), and discovering that for a given object, they are proportional. This is called Volta’s Law of Capacitance, and it was for this work that the unit of electrical potential has been named the volt.

In 1779 he became a professor of experimental physics at the University of Pavia, a chair that he occupied for almost 40 years.

Luigi Galvani, also an Italian physicist and Volta’s main rival, discovered a property he named “animal electricity” when two different metals were connected in series with a frog’s leg and to one another. Volta realized that the frog’s leg served as both a conductor of electricity (what we would now call an electrolyte) and as a detector of electricity, and that the frog’s animal nature was not relevant to the process. He replaced the frog’s leg with brine-soaked paper, and detected the flow of electricity by other means familiar to him from his previous studies.

<Fair warning> a few paragraphs of science follow for those who are interested.

In this way he discovered the electrochemical series, and the law that the electromotive force (emf) of a galvanic cell, consisting of a pair of metal electrodes separated by electrolyte, is the difference between their two electrode potentials (thus, two identical electrodes and a common electrolyte give zero net emf). This is sometimes called Volta’s Law of the electrochemical series.

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In 1800, as the result of a professional disagreement over the galvanic response advocated by Galvani, Volta invented the voltaic pile, an early electric battery, which produced a steady electric current. Volta had determined that the most effective pair of dissimilar metals to produce electricity was zinc and copper. Initially he experimented with individual cells in series, each cell being a wine goblet filled with brine into which the two dissimilar electrodes were dipped. The voltaic pile replaced the goblets with cardboard soaked in brine.

The battery made by Volta is credited as the first electrochemical cell. It consists of two electrodes: one made of zinc, the other of copper. The electrolyte is either sulfuric acid mixed with water or a form of saltwater brine. The electrolyte exists in the form 2H+ and SO42−. The zinc, which is higher in the electrochemical series than both copper and hydrogen, reacts with the negatively charged sulfate (SO42−). The positively charged hydrogen ions (protons) capture electrons from the copper, forming bubbles of hydrogen gas, H2. This makes the zinc rod the negative electrode and the copper rod the positive electrode.

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Thus, there are two terminals, and an electric current will flow if they are connected. The chemical reactions in this voltaic cell are as follows:

Zinc:

Zn → Zn2+ + 2e

Sulfuric acid:

2H+ + 2e → H2

The copper does not react, but rather it functions as an electrode for the electric current.

However, this cell also has some disadvantages. It is unsafe to handle, since sulfuric acid, even if diluted, can be hazardous. Also, the power of the cell diminishes over time because the hydrogen gas is not released. Instead, it accumulates on the surface of the zinc electrode and forms a barrier between the metal and the electrolyte solution.

<Fair warning ends>

With this invention Volta proved that electricity could be generated chemically and discounted the prevalent theory that electricity was generated solely by living beings. Volta’s invention sparked a great amount of scientific excitement and led others to conduct similar experiments which eventually led to the development of the field of electrochemistry.

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Volta drew the admiration of Napoleon Bonaparte for his invention, and was invited to the Institute of France to demonstrate his invention to the members of the Institute. Volta enjoyed a certain amount of closeness with the Emperor throughout his life who conferred numerous honours by him, including being made a count in 1810.

Volta retired in 1819 to his estate in Camnago, a frazione of Como, Italy, now named “Camnago Volta” in his honor. He died there on 5 March 1827, just after his 82nd birthday. Volta was buried in Camnago Volta.

Volta’s home town of Como is famous for its fish dishes made with fish from Lake Como. These include polenta e misultin (Alosa agone) featuring Como’s own style of polenta with shad, and risotto con filetti di pesce persico – persico is European perch (Perca fluviatilis). If you can read Italian you’ll find a good recipe here with numerous pictures as a guide http://ricette.giallozafferano.it/Risotto-al-pesce-persico.html . The dish is interesting because it features perch both in the rice and fried on top. As is common in some parts of northern Italy, the risotto may be creamy or drier – cook’s choice. This recipe uses carnaroli rice which is somewhat dry. Don’t be confused, as I was, when reading the recipe; il fumetto can mean cartoon or broth. Here you need broth !!! Make the broth with the bones and scraps from the fish you use for the dish. Be warned, making risotto properly takes years of practice.

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Risotto con Filetti di Pesce Persico

Ingredients

250 g perch fillet
320 g carnaroli rice
30 g carrots, finely diced
30 g celery, finely diced
30 g red onions, finely diced
1L fish stock
60 ml wine white
1 tsp sage
1 tsp rosemary
1 tsp thyme
45 g extra virgin olive oil
1 clove garlic, minced
15 g butter, cut in small chunks
salt and white pepper
grated zest of 1 lemon

Instructions

Have the broth simmering gently in a separate pan on the stove, keeping a ladle handy.

Cut half the fish in small chunks and keep the other half as whole fillets.

Heat the oil in a large, heavy skillet over medium heat, add the garlic for a few minutes, then remove it with a slotted spoon. Next add the carrots, celery and onion, sauté until wilted then add a ladle of broth. Let the broth evaporate, then add the herbs and rice. Toast the rice for a few minutes then add the wine and a little broth.

Here’s the part that takes practice. You must let the broth almost evaporate and then add another ladle until the rice cooks. The amount of heat is very tricky. It should not be so hot that the broth evaporates immediately, nor so low that the broth takes a long time to heat through. Keep evaporating and ladling broth until the rice is cooked but moist. During the cooking process you must keep stirring the rice.

Towards the end of the cooking process add the fish chunks, salt and pepper to taste, and lemon zest to the rice.

Meanwhile, if you have four hands, fry the whole fillets of fish to a light golden.

Remove the cooked rice from the heat and add the butter. Stir to melt. Serve the risotto on a warmed serving platter with the fried fillets on top.

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