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Home , Electrolysis, Humphry Davy, Werner von Siemens, Wilhelm Eduard Weber

THE GAS DISCHARGE IN THE (PART I) – by Julia Cipo, Holger Kersten –

Sir Vasily Humphry Petrov * July 19th, 1761 in Oboyan, Davy † August 5th, 1834 in , Russia * December 17th, 1778 in , in England Vasily Vladimirovich Petrov was a russian and member of the Russian † May 29th, 1829 in Genf, *4 Academy of Sciences. After A.Volta introduced his voltaic battery in the year *1 1800, Petrov began constructing a larger battery by using 4200 and Sir was an english , inventor and presi- discs, stowed in four huge boxes. The boxes were about 3 m long and placed dent of the Royal Society. Unaware of Petrov’s work, Davy con- parallel to each other. They alternately ended with zinc and copper, so when structed a larger voltaic battery with an area of 80 m2. connected they could be used as a serial circuit of Using his huge battery in 1807 he could decompose and 4200 electric cells. The motivation of building an soda by gaining the and . Later he could “enormous” battery as called by Petrov was the obtain , , and . During these observation of new effects. In his report of the experiments he experienced new gas discharge phenomena such year 1803 “Announcements on Galvano-Volta- as continuous arcs, which he presented often in front of a large ic experiments” he describes the observation of aristocratic audience. In his Bakerian Lecture he writes: “By the ar- *5 the fi rst continuous arc discharge. First Petrov rangement some brilliant phenomena were produced. The potash Davy’s battery used and later he replaced appeared to be a conductor in a high degree, and as long as the them with electrodes. Then he noticed communication was preserved, a most intense was exhibited melting, burning and erosion of the metal as- at the negative wire, and a column of fl ame, which seemed to be suming the use of voltaic batteries in smelt- owing to the development of combustible matter, arose from the *2 ing, and in the producing of pure point of contact.” Using his results he invented the , a metallic . Unfortunately he published gas discharge lamp with , which was used as a safety his works in russian, which is why his publi- Petrov’s battery lamp for the workers in mines. cations did not become very popular. *6 Cover page of Petrov’s report “Announcements on *3 Galvano-Voltaic experiments”, published in 1803

*7 Michael Davy’s presentations Davy’s lamp Faraday Carl Friedrich * September 22nd, 1791 in Newington Butts, Surrey, England † August 25th, 1867 in Hampton Court, Surrey, England * April 30th, 1777 in Braunschweig, Germany was an english scientist, inventor, assistant of Hum- † February 23th, 1855 in Göttingen, Germany phry Davy and member of the Royal Society. Besides his discoveries about the , the electromagnetic induction, the diamagnetism was a german mathematician, astronomer, physicist and as well as inventing the terms ‘’ and ‘’, he investigated *8 a student of Georg Christoph Lichtenberg. Gauss invented a lot of laws, mathe- the in thinned gases during the years 1831-1835. Us- matical computational methods and studied the Earth’s magnetic fi eld. To mea- *10 ing different gases like , and a gas mixture as air, he noticed glow discharges with its beginning at sure the daily fl uctuations of the magnetic fi eld, he constructed in 1832 a device the cathode and its end at the anode. As he lowered the gas pressure, he noticed a dark spot between the negative called the magnetometer. In the observatory of Göttingen Gauss and his assis- glow and the cathode, also known as the “Faraday dark tant Wilhelm Eduard did researches and measurements during the period 1836-1841. space”. There the secondary , emitted through the Some of the measurements were taken for 44 hours in a row. Because his work fascinated phys- impact of positive with the cathode, have been slowed icists worldwide, he sustained help from over 50 scientists from different continents. The mea- down, making them unable for a collision with other gas surements were taken worldwide and sent to Gauss in Göttingen, where he evaluated them. particles. In the year 1857 Faraday observed discharge In his works “Resultate aus den Beobachtungen des magnetischen Vereins” (“Results from the and also defl agration phenomena by using a wire observations of the magnetic association”) and in a hydrogen fi lled glass tube, all connected to a voltaic “Allgemeine Theorie des Erdmagnetismus” (“The battery. He predicted that his “defl agrator” could be use common theory of Earth ”) from the for fi lm deposition. year 1839 he tries to explain the observed daily *9 fl uctuations. For Gauss they are a consequence Discharge tube, Faraday Dark Space of electrical discharge happening in a conductive layer of the atmosphere. Another side effect of this discharge, which confi rms his theory was the existence of Aurora Borealis (Northern ). *11 *12 Julius Magnetometer blueprint “The common theory of Earth magnetism”, 1839 Plücker Ernest Werner * June 16th, 1801 in Elberfeld by Wuppertal, Germany † May 22nd, 1868 in Bonn, Germany von Julius Plücker was a german mathematician, physicist electrical discharges *13 and foreign member of the Royal Society. Inspired by the by applying a high * December 13th, 1816 in Lenthe by Hannover work of Michael Faraday on and af- .He want- *12† December 6th, 1892 in ter exchanging a lot of letters with the english scientist, ed to discover more *15 he started experimenting with geissler tubes, invented bei about the magnetic Ernest was a german inventor, industrialist and founder of the Heinrich Geissler, which was the glassblower for Professor properties of gases electrical company Siemens. In the year 1857 Siemens invented the generator Julius Plücker. The advantages of the geissler tubes were and their discharges. as a device for cleaning. The fi rst ozone generator consists of two with each the low air pressure within, making the geissler tubes the So 1858 he placed a other connected glass tubes, both of them coated with a metal layer. The inside of fi rst ones with a good vacuum inside of it. This way Julius close to the the generator can be fi lled with air or only with oxygen. The metal parts of tubes are Plücker could use different kind of gases for generating glass tube and no- Magnet close to a Geissler tube connected with an induction apparatus and the whole generator is placed inside of *16 ticed the shifting of a fl uid like water. When Siemens applied a high alternating voltage on this fl uid me- the glowing rays. With this work he approved that the dium, he observed a lightning discharge inside of the gas tube. As he raised the current, he notices that he obtained glow discharge has electrical properties. In 1862 he rec- ozone instead of oxygen. ognized, that the same gas could dispose over different spectra at different temperatures. He was the fi rst to rec- ognize the three lines of the hydrogen spectrum and so he *14 opened the way for the development of spectral analysis and atomic physics.

H2 spectral lines

Sources: 1- rus-eng.org, 2- “Cathodic Arcs: From Fractal Spots to energetic Condensation” by André Anders, 3- “From history of II” by Alexander Mikerov, 4- Popular Science Monthly Volume 14 , 5- scitechantiques.com, 6- “Cathodic Arcs: From Fractal Spots to energetic Condensation” by André Anders, 7- “Bibliothek allgemeinen und praktischen Wissens für Militäranwärter” Volume III, 1905 , 8- learn-math.info, 9- L.B.Loeb, Fundamental Processes in Electrical Discharges in Gases, 1939, New York, 10- www.gauss-goettingen.de, 11- Niedersächsische Staats- und Universitätsbibliothek Göttingen, 12- Springer Verlag, 13- Hausdorff Center for Mathematics, 14- LibreTexts, 15- Purdue University, College of Science, 16- Siemens.com, 17- The Hellenic Archives of Scientifi c Instruments, 18- The Hellenic Archives of Scientifi c Instruments *17 *18 Ozon generator The original Siemens ozoniser