Biography of Pierre and Marie Curie | Discovery of radioactivity

His research on the radioactivity threw new light on the nature of the atom and allowed numerous applications.
The Parisian Sorbonne University students, to cross in the corridors with the young Polish woman who had enrolled in the fall of 1891 at the Faculty of physics, wondered: "Who's that girl's shy appearance and obstinate expression dressing so poorly?". Everyone looked at her puzzled, with a mixture of sympathy and disdain. Some knew that it was called Manya Sklodowska and called it "the foreign surname impossible"; others preferred to call it simply "the silent student". Manya always sitting in the front row, had no friends and was only interested in the books. Also his beautiful Ash Blonde color hair, which used to be collected and semi-covert drew attention. No one suspected that this young woman dodges and austere would become one day, under the name of madame Curie, a distinguished woman and a national glory of France.
You manya Sklodowska, who then it would be known as Marie Curie was born in Warsaw on November 7, 1867. He was the youngest of five children (four women and a man) of a marriage that is dedicated to teaching: his father was a high school physics and math teacher and his mother Director of a school for young ladies. His childhood was marked by the coincidence with a relentless period of Russification of Poland, due to which his father had to leave the post of sub-inspector occupied in an Institute; economic necessity forced him to take as guests to school-age boys, who also gave private lessons.

Marie Curie (c. 1898)
The older sister of Manya died in 1876, victim of an epidemic of typhus, and two years later his mother because of a tuberculosis died. In 1883, after completing his secondary education, Manya suffered a nervous depression which had to recover passing close to a year in the field, in house of some relatives. Upon his return to Warsaw in 1884, he gave private lessons at her home along with her sisters and attended classes of the 'flying University» created there, aside from the Russian education system, by the impulse of a circle of positivists inspired by the teachings of Comte.
The narrowness of the family forced Manya to start working as a governess; After a first job was a failure, on January 1, 1886 entered in the service of the Zorawski, a wealthy family residing in Szczuki, North of Warsaw, where Manya had to deal with two of the daughters education. There he had the opportunity to put into practice the social ideals born in Warsaw last year organizing a school for the children of workers and peasants that spent their free hours, with the complacency of the Zorawski; the rest of his time occupied it in the study of physics and mathematics.
Manya then lived their first romantic relationship with the eldest son Zorawski, relationship that is possibly frustrated by the social differences between them; his condition nervous and prone to anxiety endured bad episode, who came to join the massive effort developed in its triple occupation of governess, master and student, doing all this, at the age of twenty, became a bitter person. When it finally ended its contract in Szczuki, in the summer of 1889, he returned to Warsaw, where he worked again as a governess for a year and resumed his contacts with the clandestine University. His cousin, who had been Assistant to Mendeleev, provided him with the opportunity to complete his knowledge of chemistry in a small laboratory and put her in contact with other researchers who had known the great European scientists of the time.

Curie marriage

In March 1890 his sister Bronia, then student of medicine in Paris, urged to meet with her; Manya work had helped to finance the career of Bronia and between the two there was an agreement of reciprocity. But Manya refused, falling into one of its periods of melancholy. Year and a half later Bronia reiterated the offer; as the economic problems of the family had watered down far enough to provide you with savings, Manya decided to finally accept. In the fall of 1891 he settled in Paris, dedicated initially to update their knowledge; in 1893 he got the Bachelor's degree in physics and in 1894, helped by a scholarship, graduated in mathematics. The two first years in Paris were isolation at work and they were marked by harsh deprivations, but they had the virtue of ending their nervous problems.

Pierre Curie
In April 1894 Marie, as already was called, met Pierre Curie. Born in Paris on May 15, 1859, Pierre Curie was the second son of a medical humanist and Freethinker had allowed that their children are educated outside of traditional schooling. Together with his brother Jacques, three years older than him and whom he joined an intense emotional relationship during childhood and youth, Pierre had studied physics at the Sorbonne. The Curie brothers had investigated the possibility of transforming mechanical energy into electrical energy in the crystals, published in 1880 his first communication about the phenomenon that would later become known as piezoelectricity; Subsequently, both also demonstrated the possibility of the opposite effect (deformation of a Crystal by applying an electrical charge) and designed a quartz piezoelectric electrometer to measure electric currents of weak intensity.
In 1882, Pierre was appointed head of the Municipal School of physics and Chemistry Laboratory, institution that was still working when he met Marie and where was devoted to the theoretical study of the symmetry. In 1891 he undertook the writing of a doctoral thesis on the magnetic properties of various substances according to the temperature, thesis presented in March 1895. Marie attended the reading of the thesis and was impressed; his relationship with Pierre Curie lasted already for twelve months, during which he had been more willing than her marriage. They finally married on 26 July of that year; his daughter Irene, who later another girl, Eva would continue seven years was born in 1897.

Pierre and Marie Curie's wedding photo
After the birth of their first daughter, Marie Curie set out to write a doctoral thesis, unusual fact that then in the case of a woman. The discovery by Röntgen rays X in 1895 and the observation made in 1896 by Henri Becquerel that uranium salts, even protected from the light, emitted rays which, like x-rays, penetrating the matter, decided it to investigate the source of that energy that uranium compound used in obscure through photographic emulsions in his thesis even of metal protection. The subject had the advantage of being a still virgin land in scientific research.


The director of Pierre Curie agreed that Marie habilitase laboratory as a dependency of the Municipal School of physics and chemistry that served as a depot and engine room. There Marie Curie began their research, using the electrometer invented by Pierre and his brother to measure the intensity of the current caused by the various compounds of uranium and thorium, checking immediately that the activity of salts of uranium depended on only the amount of uranium present, regardless of other circumstances. From the scientific point of view, this was his most important discovery, because it showed that radiation could not proceed more than the atom itself, independently of any added substance or a chemical reaction. But Marie Curie is not entertained in ponder this result; It extended its investigations the pitchblende and the calcolita found with it were more active than uranium. This he deduced the existence in those other substance responsible for this increased activity, new minerals.
With the help of her husband, Marie Curie proceeded to chemically treated pitchblende until you get a product that was three hundred thirty times more active than uranium: in July 1898 marriage reported their results to the Academy of Sciences proposing the name of "polonium" for the new element, whose very existence relied on that it was confirmed, and using the term «radioactive» for the first time to describe the behavior of substances such as uranium. But subsequent investigations we are asked to believe in the existence of still another new element in the pitchblende; After the Austrian Government to provide them the purchase of several tons of ore waste from the mines of Saint Joachimsthal, dedicated to the exploitation of uranium, the existence of the item called «radio», announced in December of the same year, was confirmed; your atomic weight was established by Marie Curie in March 1902 as equal to 225,93.

Marie and Pierre Curie in his laboratory
Meanwhile, in 1900 the financial concerns of the marriage were relatively relieved by the appointment of Pierre for a Chair in physics at the Sorbonne, at the initiative of the mathematician Henri Pinchare; Marie, for his part, occupied a place of Professor of physics at the Ecole Normale Superieure de Sèvres; However, his teaching stole them time for experimental research. They also had material facilities for them; carried out in precarious conditions, they believed a tiring physical exertion. This was compounded by problems arising from exposure to radioactivity, whose consequences were unaware. Radioactivity produced les visible lesions on the hands, and would be ultimately responsible for the leukemia as a result of which died Marie Curie.
Ironically, the healing properties that, initially, were attributed to radioactivity, contributed to his fame. Scientific recognition came in 1903 with the award of the Royal Society's Davy Medal and the Nobel Prize in physics, shared with Becquerel. The Curie did not go personally to pick it to Stockholm since his health, in the case of Marie, had been affected by the loss of a child born prematurely.


The effects of the reception of the Nobel were overwhelming for the Curie, which were converted into the public spotlight by expectations aroused by the radioactive phenomena. With all earned Pierre creation in 1904 of a specific Chair for him, equipped with a laboratory that Marie would take over. That same year, a French industrialist created a factory aimed at obtaining the radio using the tips of the marriage. Although they never had the resources to equip a laboratory suited to their needs, the Curie always refused to patent the commercial production of the substance.
In 1906 Pierre Curie died tragically in Paris hit by a carriage; the event became a person distant from his friends (but not daughters) to Marie, although it continued its work and succeeded her husband in the Chair which had only been able to deal with year and means, becoming thus becoming the first woman in France who entered higher education. In 1910 he published the treatise on radioactivity and prepared an international pattern of the radio which deposited at the International Bureau of weights and measures in Paris in 1911.
That year received for the second time the Nobel Prize, this time in chemistry for the discovery of radium and polonium; It was the first time that a scientist deserved the Award twice. It seems that in the decision of the Swedish Academy could influence that he had failed the nomination of Marie Curie to the French Academy of Sciences, as well as the fact of having been the victim of a journalistic scandal concerning his relationship with Paul Langevin, French physicist who had been a disciple of Pierre Curie.

Irene and Marie Curie in the Radio Institute (1921)
In the majority of European countries began to create institutes of the radio, before its plausible utility in the treatment of cancer. The Marie Curie own accepted the honorary direction of which was opened in Warsaw in 1913; the construction of a laboratory devoted to the study of radioactivity, the Institute of Radio, by an agreement between the Institut Pasteur and the Sorbonne, with a section devoted to medical research and another reserved for physics and chemistry, directed by Marie Curie, was completed in Paris in July of the following year. During the first world war created, with the help of private donations, a team of experts in radiographic techniques, and with the collaboration of his daughter Irene, put into operation more than two hundred radiological vehicles; mother and daughter moved to the front to teach doctors new methods and techniques of Radiology.
In May 1921 Marie Curie toured, along with their daughters, triumphant United States in order to collect the gram of radio (valued then at $100,000) which had made it possible for the popular subscription promoted by a journalist. On his return began to manifest itself in Marie early symptoms that suffered from cataracts, and the suspicion that radio emissions could produce something more than burns fingers began to take shape, even though the hope that had a permanent effect on the cancer cells was then at its peak.

Curie and physicist Robert Millikan in Congress
Nuclear Physics of Rome (1931)
In 1922 she was invited to be part of the Commission for intellectual cooperation created by the League of Nations, which occupied the Vice-Presidency. In 1925 his daughter Irene married French physicist Frédéric Joliot; in January 1934, both discovered artificial radioactivity, discovery whereby they would receive in 1935 Nobel Prize for Chemistry, the third of the deserved by the family. A few months after the discovery, the health of Marie Curie has definitely deteriorated. Believing that it was inflammation of ancient tuberculous lesions, was taken to a sanatorium in Sancellemoz; There he was diagnosed pernicious anemia, and died July 4, 1934. His daughter Irene also died of leukemia in 1956; her husband acknowledged that death was a result of the radiation, although it held that the liver condition that would cost himself the life two years later had nothing to do with radioactivity.
When, during the first world war, Marie toured hospitals to assist surgeons with radiological techniques (thanks to x-rays could be discovered bullets and shrapnel fragments hidden in the wounded), their invaluable help was that it began to be called "Beneficial Supreme of humanity". Marie always rejected these manifestations, that considered undeserved: remained so modest and unobtrusive as when he was only a young Polish student at the Sorbonne. Einstein, who met after the war and maintained a fruitful scientific relationship with her, said: 'Madame Curie is, of all the celebrities, the only one that glory has not corrupted'.

Chronology of Pierre and Marie Curie

1859Born Pierre Curie in Paris.
1867Born Marie Sklodowska in Warsaw.
1882Pierre was appointed head of the Municipal School of physics and chemistry laboratory.
1886-89Marie works as a governess of the Zorawski Szczuki.
1891Marie moved to Paris and began his studies of physics at the Sorbonne. Pierre undertakes the preparation of his doctoral thesis.
1893Marie license in physics with the number one valedictorian and, a year later, in mathematics.
1895A year after, Marie and Pierre marry.
1897Their daughter Irene is born.
1898They discover radioactivity and two new elements, polonium and radium.
1900Pierre obtained the Chair of physics at the Sorbonne.
1903They receive the Nobel Prize in physics.
1904His daughter Eva is born.
1906Pierre Curie died in Paris, run over by a carriage. Marie happens to you in your Chair.
1910Marie published the treatise on radioactivity.
1911Marie receives the Nobel Prize of chemistry.
1914The Institute of the Radio in Paris, whose scientific section directs Marie was created.
1914-18Create a team of experts in radiology to help physicians in hospitals.
1921Travel to United States. It starts to deteriorate their health.
1925His daughter Irene married the physicist Frédéric Joliot.
1934Death of Marie in Sancellemoz.
1935Irene Curie and Frédéric Joliot received the Nobel Prize in chemistry for their discovery of artificial radioactivity.

Pierre and Marie Curie: discovery of radioactivity


Radioactivity is the emission of radiation from unstable nuclei. Such radiation can occur in the form of subatomic particles (primarily alpha particles and beta) or in the form of energy (mainly gamma). By chance, the French physicist Henri Becquerel (1852-1908) discovered the existence of this type of radiation in 1896. In the decades since the discovery of Becquerel, the study of radioactivity gave rise to different developments that revolutionized the understanding of the nature of matter and led to the introduction of numerous practical applications of importance. These applications include many new devices and industries ranging from weapons and nuclear power plants to a wide variety of medical techniques used in the diagnosis and treatment of diseases.

Henri Becquerel
In 1896, when he was studying the relationship between fluorescence and emission of x-rays in a uranium salt, Becquerel found that the radiations emitted were similar to X rays but had nothing to do with fluorescence, since emission depended not on the salt in the light exposure and was only produced by uranium salts , while other fluorescent substances do not broadcast it. The rays emitted were called Becquerel rays.
The phenomenon discovered by Becquerel was studied by Pierre and Marie Curie, husbands who the most important contributions to the knowledge of the phenomenon. Marie Curie researched elements emitted Becquerel rays. By measuring the intensity of the radiation emitted by all the known elements, found that only thorium and uranium emitted radiation (currently 40 are known) and named the phenomenon with the name of radioactivity (today radioactivity preferred form). The intensity of the radiation was proportional to the amount of emitting element, it was deduced that the phenomenon was an atomic property. He noted that some uranium ores were most active from what would have been if the issuing activity was due to uranium and assumed the existence of an element unknown with a far superior to the uranium source capacity. This hypothesis was confirmed with the discovery of two new elements, polonium and radium.
In 1899, Rutherford exposed to the action of a magnetic field the radiation emitted by a radioactive element. It was found that they were constituted by two types of particles: a little penetrating and positive nature, called alpha rays, and other more pervasive and negative character, called beta rays. In 1900, Paul Ulrich Villard (1860-1934) repeated the experiment using a more powerful magnetic field and discovered that a percentage of the radiation was not deflected by the field. It was a few rays similar to X rays that Rutherford, in 1903, called gamma rays; the own Rutherford showed that they consisted of electromagnetic waves.

Ernest Rutherford
All atomic nucleus (with the exception of hydrogen) contains one or more protons, and one or more neutrons. The nuclei of most atoms of carbon, for example, contain six protons and six neutrons. The nuclei of the atoms tend to be stable, i.e. does not spontaneously undergo no change. Within a hundred years, or one million years, a carbon core will retain exactly the same appearance that today has. Some nuclei, however, are unstable. An unstable nucleus is one that spontaneously undergoes internal changes. This change occurs, kernel emitted a subatomic particle, or apparent power, or both. An example of unstable nucleus is carbon-14, an isotope of carbon whose nucleus consists of 6 protons and 8 neutrons (instead of 6). A core which emits a particle or that exudes energy reportedly undergoing radioactive decay or, simply, that it disintegrates.
He is not known with certainty what determines the instability of a nucleus. Apparently, some nuclei have an excessive number of protons or neutrons, or an excessive amount of energy; These cores restored the proper balance of protons, neutrons, and energy that corresponds to them by emitting a subatomic particle or releasing energy. In the process, the nucleus varies its composition and can, in fact, become a core completely different. Carbon-14, for example, when trying to achieve its stability emits a beta particle. After losing that particle, the core of carbon-14 has 7 protons and 7 neutrons. But a kernel with 7 protons and 7 neutrons is not a carbon core: is the nucleus of an atom of nitrogen. By a particle emitting beta, carbon-14 atom has been transformed in a nitrogen atom.
In the majority of cases, the forms of radiation emitted by a radioactive nucleus are alpha particles, beta particles, and gamma rays. An alpha particle is the nucleus of a helium atom, which consists of 2 protons and 2 neutrons. Consider the case of the radio-226. The nucleus of an atom of 226 radio consists of 88 protons and 138 neutrons; for the nucleus emits an alpha particle it has to get rid of 2 protons and 2 neutrons, which are those that form the particle. Following the issuance of the alpha particle the resulting nucleus contains only 86 protons (88 - 2) and 136 neutrons (138 - 2). This core is an atom of radon, rather than an atom of radio. By emitting an alpha particle, Atom radio-226 has been transformed into an atom of radon.
For many years, the emission of particulates by a core beta was puzzlement for scientists. A beta particle is an electron. The problem lies in the fact that the nuclei of the atoms contain electrons; These are located on the outside of the kernel, but not within it. Then how can a unstable core issue a particle (an electron) beta? The answer is that the particle beta is produced by the decay of a neutron inside of the atomic nucleus, forming a proton and an electron. A proton carries a positive charge, and an electron unit, a unit of negative charge. This means that a neutron, which carries no electrical charge, can decompose forming two new particles (a proton and an electron) whose electrical loads add up to zero.
Consider again the example of the aforementioned carbon-14. A carbon-14 nucleus disintegrates by a particle emitting beta; This means that a neutron in the nucleus of carbon-14 decomposes to form a proton and an electron. The electron is emitted in the form of beta radiation, and the proton remains in the interior of the nucleus; in this way, the new kernel will contain 7 protons (the original 6 more new proton) and 7 neutrons (the 8 original less which has undergone the decomposition).
In an unstable nucleus, loss of an alpha particle or beta is often accompanied by the emission of gamma radiation. Gamma radiation is a form of high energy radiation; It is similar to the emission of x-rays, but with a slightly higher energy level. Some unstable nuclei can disintegrate by emitting gamma rays; After losing power in the form of gamma radiation, slipped, they become stable.

Marie Curie
Many radioactive elements exist in a natural state; others have "variants" radioactive, called radioactive isotopes. In fact, all elements heavier than bismuth (atomic number 83) are radioactive; they have no stable isotopes. The heavier radioactive elements are part of series known as radioactive families. A radioactive family is a group of elements in which the disintegration of a radioactive element produced another element that is also radioactive. The family of elements from uranium-238 isotope provides an example. When the uranium-238 disintegrates, form the thorium-234; but the thorium-234 is also radioactive and, to disintegrate, turns into Protactinium-23, which, in turn, is also radioactive and disintegrates forming uranium-234. The process continues through eleven stages, until the isotope polonium-210 disintegrates forming lead-206, which is stable.
Also many lighter elements have radioactive isotopes; among them are the hydrogen-3, carbon-14, the potassium-40 and the tellurium-123. It is also possible to get artificially radioactive isotopes. In general, this is bombarding a stable nucleus with protons, neutrons, alpha particles or other subatomic particles. The process of bombing can be performed in particle accelerators or nuclear reactors. When one of the particles used as projectiles in the bombing strikes a stable core, can become unstable and, therefore, make it radioactive.
The radioactivity is ionizing, i.e. radiation releases electrons of matter that in its path, which is used in counters to measure radioactivity. This is also the main cause of this radiation is harmful to living organisms. In general, small doses of radiation emitted by the Earth or space are harmless, but in larger quantities cause serious damage, mainly in the sexual glands and tissues of the bone marrow where blood cells are made. This requires large measures of safety in nuclear power plants, whose radioactive waste should be stored in closed containers, radiation-resistant, for hundreds of years.

Works of Pierre and Marie Curie

The numerous writings dedicated to radioactivity by Pierre and Marie Curie are among the most important works of 20th-century physics. They are the result of a close collaboration that dates back to 1895, date of their marriage. The discovery of radioactivity was the subject of some thirty of memoir, published between 1898 and 1906; six of these memoirs mentioned the explicit cooperation of Marie; others cite his colleagues G. Bémont, G. Sagnac, A. Debierne, H. Becquerel, I. Danne, Dewar, A. Laborde, ch. Bouchard and V. Balthazard.
The first notes about radioactivity, written in collaboration with his wife were on a new substance contained in the pitchblende (Comptes rendus, vol. CXXVII, p. 175; on July 18, 1895); This note had been preceded by a previous (Comptes rendus, vol. CXXXVI, p. 1.101), communicated only by Marie Curie, exposing the hypothesis that the great (superior to the uranium and thorium) activity presenting certain minerals containing these metals (pitchblende, pitchblende, calcolita), could be due to a substance contained in very small quantities at these same minerals. This first report shows made initial attempts to isolate this new substance through chemical reactions controlled by the electrometer and piezoelectric Quartz. By measuring the activity of various sulphides from the pitchblende, the Curie came to the conclusion of the existence of a new metal, which they called "polonium" as a tribute to the homeland of Marie.
The memory on a new substance strongly radioactiva contained in the pitchblende (C. R., vol. CXXVII, p. 1,215; 26 December 1898), in collaboration with G. Bémont, sets out the procedure that led to the discovery of the radio, much more active than polonium. None of the two metals was still isolated in their State of purity, but had already been studied its properties based on their sales. The report on radioactivity by Becquerel rays (C. R., tomo CXXIX, p. 174; November 6, 1899) confirms that the induced radioactivity not due to traces of the radioactive material transported in the form of dust or vapors, but to a kind of secondary radiation due to Becquerel rays; Unlike secondary Röntgen rays, starting abruptly at the very moment in which body issuing them is beaten by Röntgen rays and ceases when cease, the induced radioactivity is maintained and does not disappear but gradual and regularly.

Marie Curie in the laboratory
In the chemical effects produced by Becquerel rays (C. R., tomo CXXIX, p. 823; 20 November 1899) is designated the transformation of oxygen into ozone under the action of products radiferos bright and very active and the change in coloration of the platinocyanide of barium, among other phenomena. Electric rays detached RADIUS load memory (C. R., Tome CXLI, p. 647; 5 March 1900) complete a previous note distinguishing two kinds of rays emitted by the radio, ones which turned by the action of a magnetic field and others, and says that the first are loaded of negative electricity.
Finally, new radioactive substances and the rays that emit (Rapports present au Congrès international de Physique, 1900, volume III, p. 79), is one of the most important and the most complete of few wrote on this subject; authors summarized their previous jobs, provide all the details of their experiences and give numerical data from their research.
A later memory, on radioactive bodies (C. R., vol. CXLVI, page 85; 13 January 1902), accurate hypotheses about the origins of the energy of radioactivity. Numerous memoirs that followed these do not make express mention of the collaboration of both spouses, who remained, however, until the tragic accident that ended on April 19, 1906, to the short but glorious life of Pierre Curie (not had still forty years). All these writings were gathered, along with his other works, in the Works of Pierre Curie published under the care of the French physics society (Paris, 1908), with a preface by his wife.

The treatise on radioactivity of Marie Curie

Published in 1910, this work that emerged from the research and experiments of the author was fundamental to the development of physics. The discovery of the radioactive phenomena would result in a great revolution in the history of science to demonstrate the possibility of a disintegration of the atomic nucleus and the consequent transformation of one element in another spontaneous.
The Treaty begins with a synthetic yet complete, review of the different properties of the electrons and the Röntgen rays. On the curious manifestations that present certain minerals and that motivated the first investigations on radioactive bodies are described, and the procedures followed to isolate the radioactive elements, in particular the radio are exposed. The following chapters contain the exposition of the properties of these elements, among which are, in addition to the radio, uranium, thorium, Actinium, the Ionian and polonium.
Also studied the emissions of the three types of rays: (double positively charged helium particles) alpha rays, beta rays (negative electrons) and gamma rays (x-rays much richer in energy and therefore much more penetrating than those obtained artificially), which can be considered as waste from the destruction of the nucleus of radioactive substances , and that, therefore, always accompany the breakups of these substances.
The author lists the properties of radiation and its effects, such as the printing of photographic plates, fluorescence and phosphorescence in certain substances or air ionization. Finally describes the successive transformations of elements that, disintegrated, give rise to derived elements, which in turn generate other elements, in a continuous chain ending not more than with a stable element; the Treaty details throughout its history the three families of radioactive elements (uranium, Actinium and thorium), ending in a same descendant: the lead.

Other works by Pierre Curie

The other writings of Pierre Curie, belonging to different epochs (from 1880 to 1906) had been published in various journals and deal with different themes. The first in time is the determination of the wavelengths of low temperature heat rays; others refer to crystallography, piezoelectricity, pyroelectricity, symmetry, the formation of crystals and the constant capillaries, cushioned movements and reduced equations, the conductivity of the dielectric solids, the magnetic properties of bodies, etc.

Pierre Curie
Pierre Curie was not only a skilled experimenter, but also an inventor of machines new, including a precision scales that offer remarkable characteristics of running, a dynamometer, optical transmission, a piezoelectric pressure gauge, new electrometers of aperiodic quadrants, a static (in collaboration with R. Blondot) wattmeter, an electroscope for radioactive bodies and an apparatus for the determination of magnetic constants. His first research on crystallography had been carried out, in part, in collaboration with his brother Jacques.
All the writings of Curie are the great care put in the text, a perfect shape and a great clarity and conciseness in accurate exposure of the subject. Conciseness reveals itself especially in theoretical reports on questions of order and symmetry: a clear, and full study carried out by introducing the new concept of translational or rotational symmetry plane, generalizing the laws of symmetry by their application to the States of the space created by physical agents; particular establishes what is symmetry characteristic which must be attributed to a State of electric field and a magnetic field status. In the course of a long series of investigations on the magnetic properties of bodies, since the ordinary temperature than 1,400 °, for weakly magnetic bodies established the law that bears his name (the coefficient of magnetism is inversely proportional to the absolute temperature).
The discovery of piezoelectricity, phenomenon whereby electricity development occurs in crystals of a center of symmetry under the action of a mechanical deformation, dragged to the Curie brothers to a series of extremely delicate work on electrostatics, work which led to the improvement of the technique of electrical measurements, by means of the electrometer that bears his name. Piezoelectric quartz, that allows to reproduce a quantity of electricity known in absolute value, can serve as a basis for the measurement of quantities of electricity and as an instrument of absolute measure electrical loads and weak currents. Large services is provided by their virtues to the Curie in their research on radioactivity.
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