Biographical encyclopedia
Download 17.33 Mb. Pdf ko'rish
|
- Bu sahifa navigatsiya:
- SCHWEIGGER
|
281 [418] CANDOLLE
GAY-LUSSAC [420] bustion engine was to change it half a century later. Oersted did not keep up with the whirlwind of activity his experiment had stirred up. He did show that the force of the current on the needle made itself felt through glass, metals, and other nonmag netic substances, but except for that, he did nothing further to follow up his own momentous discovery. Nevertheless, the unit of magnetic field strength was officially named the “oersted” in his honor in 1934. Outside electromagnetics, Oersted was the first to isolate the organic compound piperidine (1820) and the first to pre pare metallic aluminum (1825). [418] CANDOLLE, Augustin Pyrame de (kahn-doleO Swiss-French botanist
Candolle was a member of a Hu guenot family that had fled France at the time of the religious wars to escape per secution. Once the French Revolution ended religious disabilities, young Can dolle settled in Paris in 1796 and there obtained his medical degree at the Uni versity of Paris in 1804. He was ap pointed professor of botany at the Uni versity of Montpellier in 1808. He began working on a large plant en cyclopedia, which attracted the favorable attention of Lamarck [336] and Cuvier [396], It turned out to be enormous and more than a lifetime of work. Candolle published seven volumes before his death (his son saw to the publication of the remaining fourteen). His reputation was firmly established by the early volumes and he spent six years making a botani cal and agricultural survey of France at the express request of the French gov ernment.
Candolle introduced Jussieu [345] and Cuvier’s system of classification by deep- lying similarities into the plant kingdom. He spent the rest of his life extending and perfecting this system. It was he who invented the word “taxonomy” in 1813 to describe the science of classifica tion. His system of plant classification is largely in use today. In 1819 he accepted a professorship in botany at the University of Geneva and there remained for the rest of his life. Like Cuvier, Candolle was firmly an tievolutionary. [419] BRETONNEAU, Pierre Fidèle (breh-tuh-noh') French physician
3, 1778
Died: Passy, February 18, 1862 Bretonneau was the son of a master surgeon, but his education was very hap hazard indeed. Nevertheless, he finally managed to obtain his M.D. degree in 1815.
He did some important medical work. From 1818 to 1820 an epidemic of diph theria ravaged Tours. Bretonneau worked hard during that time and ex amined carefully. He was the first to study the symptoms of the disease thor oughly and, indeed, gave it its present name, “diphtheria,” in 1826. He took the name from the Greek word for “leather” or “parchment” because of the parchmentlike membrane that formed in the course of the disease. To prevent the fatal asphyxia that that membrane pro duced, Bretonneau performed a tracheot omy on a four-year-old girl in July 1825, cutting an opening into the wind pipe through the skin and muscles of the neck. It was the first operation of its kind and it was successful. Bretonneau also distinguished between typhus fever and typhoid (“typhuslike”) fever. His speculations on the communi cability of disease foreshadowed the germ theory of Pasteur [642] a genera tion later. [420] GAY-LUSSAC, Joseph Louis (gay'lyoo-sakO French chemist Born: St. Léonard, Haute Vienne, December 6, 1778 Died: Paris, May 9, 1850 282 [420] GAY-LUSSAC GAY-LUSSAC
As a young man, Gay-Lussac, the son of a judge who was imprisoned for a time because of royalist sympathies dur ing the French Revolution, studied at the École Polytechnique under Berthollet [346], Guyton de Morveau [319] and Fourcroy [366]. He graduated in 1800. While in school, Gay-Lussac was par ticularly befriended and encouraged by Berthollet, and for a while he worked along with Berthollet’s son in a factory where chlorine was used to bleach linen. Gay-Lussac proved himself worthy of the friendship soon enough. In 1802 he showed that different gases all expanded by equal amounts with rise in temperature. Charles [343] had made the same discovery some years earlier but had not published it; the credit therefore belongs to Gay-Lussac at least as much, and probably more and the phenomenon is frequently called Gay- Lussac’s law. This was an extremely im portant discovery, which Avogadro [412] was to use within the decade to formu late his long-neglected hypothesis that equal volumes of different gases at equal temperatures contained equal numbers of particles. In 1804 the young Gay-Lussac made a balloon ascension with Biot [404] and later made one on his own. These were among the first ascents for scientific pur poses. Gay-Lussac reached a height of four miles, higher than the tallest peak of the Alps, in one of these flights. He found no change either in the composi tion of the air or in the earth’s magnetic force. In 1805 and 1806, he traveled with Humboldt [397] measuring terres trial magnetism. At this time England was the spear head of continued attempts on the part of various European powers to unseat Napoleon. England was also the center of astonishing chemical advances made by Davy [421], who in 1807 and 1808 was isolating a number of new elements through the action of electricity. In the wake of the French Revolution, nationalism had become strong enough for governments to wish to make deliber ate attempts to harness science to the cause of national prestige. Napoleon pro vided Gay-Lussac and his long-time friend and co-worker Thénard [416] with funds for building a powerful battery as a source of a large electric current in order that France might close the “ele ment gap.” The battery proved unnecessary. Gay- Lussac and Thénard made use of one of Davy’s own elements, potassium, to do the job without electricity. By treating boron oxide with potassium, they liber ated boron, for the first time, in elemen tary form. They announced this on June 21, 1808. Davy was beaten by nine days: He announced the independent isolation of boron on June 30. Napoleon had his scientific victory, and Gay-Lus sac was appointed professor of physics at the Sorbonne, a post he held till 1832. Gay-Lussac went on to make more im portant discoveries. In 1809 he found that in forming compounds, gases com bined in proportions by volume that could be expressed in small whole num bers. For instance, two parts of hydrogen united with one part of oxygen to form water; one part of hydrogen united with one part of chlorine to form hydrogen chloride; and three parts of hydrogen united with one part of nitrogen to form ammonia. This law of combining vol umes was worked out, in part, with the help of the universally talented Hum boldt [397]. This relationship by volume of the ele ments in a compound could be used most fruitfully in the determination of atomic weights, and this Berzelius [425] went on to do. However, Dalton [389] refused to accept Gay-Lussac’s results and stuck firmly to the principle of com position by weight only and his atomic weights continued to be wrong. Avoga- dro’s hypothesis came along within two years to explain Gay-Lussac’s law, but it was ignored for half a century. Gay-Lussac then began a series of researches on cyanides, which ended with the conclusive proof that prussic acid, or hydrogen cyanide, contained no oxygen. This finally showed that acids could be acids without the presence of oxygen and demonstrated that in this re spect at least, Lavoisier [334] was wrong.
[421] DAVY
DAVY [421] (As it turned out, hydrogen is the essen tial element of acids.) Gay-Lussac also followed up Cour- tois’s [414] discovery of iodine and showed it to be a new element (entering into a dispute with Davy over priority in this matter). He added new techniques to the armory of the analytical chemist through the use of titrations (careful ad dition of exact volumes) involving alkali and chlorine. As early as 1811 he and Thénard used their analytical skill to de termine the elementary composition of sugar for the first time. In 1831 Gay-Lussac was elected to the French Chamber of Deputies under the new regime of Louis-Philippe and spent his later years as a lawmaker, entering the upper house, the Chamber of Peers in 1839. [421] DAVY, Sir Humphry English chemist
cember 17, 1778 Died: Geneva, Switzerland, May 29, 1829 Davy, the son of a woodcarver, spent his youth in poverty. His father died leaving a £1,300 debt as legacy—one that young Davy and his mother eventu ally paid off in full. He did not enjoy school and was soon apprenticed to an apothecary. At the apothecary’s he began a course of self-education and was discharged when this led him into con ducting chemical reactions that ended in explosions. His interests were, at first, rather wide- ranging. He was an enthusiastic fisher man and wrote a book on the subject. He was interested in philosophy and is considered to have displayed consid erable talent as a poet; later in life he was befriended and respected by such lit erary lights as Wordsworth and Cole ridge.
However, in 1797 he read Lavoisier’s [334] textbook on chemistry and thereaf ter he was a chemist. Upon completing his apprenticeship, Davy was recom mended to a physician who had just es tablished an institution for the study of the therapeutic properties of gases. At the age of twenty, Davy became superin tendent of the institution. Within a year he had experimented with heat and had disagreed with Lavoi sier’s caloric theory, maintaining instead that heat was a form of motion. He also experimented with gases, using instru ments made for him by Watt [316] and nearly killing himself with the more poi sonous ones. He felt something was to be gained by breathing his products and ob serving the results. He breathed four quarts of hydrogen, for instance, nearly to the point of his own suffocation and tried to breathe pure carbon dioxide. (The connection with Watt, by the way, was not accidental. Davy was bom in Cornwall, where Watt’s steam engine first gained fame. Watt’s second son, Gregory, lodged with Davy’s mother.) At least once, Davy’s foolishly risky inhalation experiments paid off. He stud ied nitrous oxide in 1800 and reported upon its unusual properties. On being inhaled, it gave rise to a giddy, intoxi cated feeling. Inhibitions were lowered so that subjects would laugh easily, cry, or go into other emotional exhibitions when those were suggested. (Hence, it is often called laughing gas.) For a while, nitrous oxide parties were all the rage among those who could think of nothing more worthwhile to do. It was almost the LSD of its day and Davy’s poet friend Robert Southey was one of those who tried it and then wrote up his expe riences of being “turned on.” Much more important was the fact that nitrous oxide was to serve as the first chemical anesthetic (and it is still sometimes so used in dentistry). In 1801 Rumford [360] needed a lec turer at the newly founded Royal Institu tion in London. Doubtfully he tested Davy, but upon hearing the young pro vincial lecturer he hired him at once, and by the next year Davy was a pro fessor. Rumford soon quarreled with others backing the institution (which had financial problems) and left En gland. Davy took over. He prepared and polished his talks to the last syllable
[421] DAVY
DAVY [421] and proved a delightful lecturer, with the poise and charm of a bom showman. Some historians of science maintain him to have been the handsomest of all the great scientists. The Napoleonic Wars were keeping the English gentry at home and London society, particularly the ladies, flocked to hear the handsome young man talk about the new principles of chemistry. The institution began to do famously and soon no longer had financial difficul ties.
During this time he worked on agricul tural chemistry. While not entirely suc cessful in the field, he eventually pub lished (in 1813) the first textbook deal ing with the applications of chemistry to agriculture. He was also interested in mineralogy and in 1807 was one of the charter members of the newly founded Geological Society of London. It was the first society of its kind in the world. His true fame was in electricity. After Nicholson [361] had broken up the water molecule by means of an electric current, Davy began to wonder about the effect of electricity on other com pounds. A number of substances such as lime, magnesia, potash, and soda were strongly suspected of possessing metallic elements as part of their structure—met als that had never been isolated. The trouble was that these metals held on so tightly to oxygen that neither strong heat nor the counterattractions of other metals for the oxygen could liberate them. Davy began his own electrical experi ments, producing an electric arc in 1805, and in 1806 was awarded a prize es tablished by Napoleon for the best work of the year in electricity. Since England was at war with Napoleonic France at the time, there was some doubt as to whether Davy should accept the medal. Davy, however, accepted, saying stoutly that the governments might be at war but the scientists were not. He then proceeded to construct a bat tery with over two hundred and fifty me tallic plates, the strongest ever built at that time, and began running electric currents first through solutions of these metal-containing materials and then through the molten substances them selves.
The results were spectacular. On Octo ber 6, 1807, the current passing through molten potash liberated a metal, which Davy called potassium. The little glob ules of shining metal tore the water molécule apart as it eagerly recombined with oxygen and the liberated hydrogen burst into lavender flame. Davy danced about in a delirium of joy. A week later he isolated sodium from soda. In 1808, by using a somewhat modified method suggested by Berzelius [425], he isolated barium, strontium, cal cium, and magnesium. He also isolated boron, but here he was beaten by nine days by Gay-Lussac [420] and Thénard [416]. His path and Gay-Lussac’s crossed at several other places. Both he and Gay-Lussac disproved Lavoisier’s conten tion that all acids had oxygen and did it at about the same time, Davy showing that hydrochloric acid had no oxygen and Gay-Lussac that prussic acid had none. Both Gay-Lussac and Davy showed that poor Courtois’s [414] io dine was indeed an element. Davy’s work with hydrochloric acid was the most impressive of these conflicts, for not only was hydrochloric acid one of the common strong acids (so that the absence of oxygen was as tonishing) but it led to his proof that chlorine was an element and contained no oxygen, despite the opinion of Scheele [329] a generation earlier. It was Davy who suggested the name chlorine —from a Greek word for “green”— because of the greenish color of the gas. He discovered, furthermore, that chlo rine could support combustion as oxygen could. It was the first indication that ox ygen was not unique in this and that there were other chemically active gases. Davy further detracted from oxygen’s importance by suggesting (correctly) that it was the content of hydrogen that was characteristic of acids. Despite his great work in chemistry, Davy could not bring himself to accept Dalton’s [389] atomic theory, even though his own close friend Wollaston
[421] DAVY
SCHWEIGGER [422] [388] was a convinced atomist and tried to convert him. In 1812 he resigned his lectureship, was knighted, promptly married a rich Scottish widow, and, the next year, was off on a tour of Europe in a blaze of fame. England and France were still at war, but the French chemists greeted him warmly. He met Rumford there once more, shortly before the latter’s death.
In a way, he needed the vacation badly. Thanks to his habit of sniffing and tasting new chemicals, he was an invalid from 1811 on, undoubtedly as a result of chemical poisoning. Then, in 1812, he damaged his eyes in a nitrogen trichlo ride explosion. It is not surprising he died in middle life. In 1815 he invented the Davy lamp, in which an open flame is surrounded by a cylinder of metallic gauze. Oxygen can get through the gauze and feed the flame. The heat of the flame, however, is dissipated by the metal and explosive gases outside the lamp are not ignited. For the first time, miners were reasona bly safe from explosion. Davy refused to patent the invention and profit from so humanitarian a discovery. However, he burst into a jealous fury when Stephen son [431]—justifiably, in the opinion of many—claimed priority in the invention. In 1818 Davy was made a baronet for this service to the mining industry. He turned his electric arc to service too, converting it into an arc lamp, the first attempt to turn electricity to the task of illumination (a task that was to reach a climax in the time of Edison [788]). Davy was also the first to take note of the catalytic ability of platinum, a phenomenon that Dobereiner [427] was to make spectacular. In 1820 Davy became president of the Royal Society, succeeding Banks [331], Davy campaigned openly for the office, which might otherwise have gone to the more diffident Wollaston, and this is an other example of Davy’s avidity for scientific honors. After 1823 Davy spent most of his time abroad and died in Switzerland. In his will he left funds to establish a medal to be given annually to chemists who had made the most important discovery of the year. Awarded in 1877 for the first time, Bunsen [565] and Kirchhofi [648] received it. Considering that those two men discovered a new way to locate new elements, as Davy had done, and in particular discovered two close relatives of Davy’s sodium and potassium, this first award was most appropriate. Davy’s chief accomplishment may not have been material. A young man named Michael Faraday [474] attended Davy’s lectures and applied for and eventually got the post of assistant, which he filled most wonderfully. It was Faraday, for instance, who skillfully prepared that most dangerous explosive, nitrogen tri chloride, which Davy, less skillful, then allowed to explode, nearly losing his eye sight as a result. In later years Faraday was considered the greatest of all Davy’s discoveries, and greater in science than his patron. Davy could sense that this would hap pen and grew jealous. In 1824 he tried to block Faraday’s election to the Royal Society but fortunately was unsuccessful. Faraday was never seduced into respond ing to Davy’s ungenerosity in kind. He was the better man in more than science. [422] SCHWEIGGER, Johann Salomo Christoph (shvigh'ger) German physicist
1779
Died: Halle, Prussian Saxony, September 6, 1857 Schweigger, the son of a professor of theology, received his Ph.D. in 1800 at the University of Erlangen. He taught at a succession of German schools and was at the University of Halle in 1820 when the news of Oersted’s [417] experiment reached him. He quickly saw that the deflection of the needle could be used to measure the strength of the current, since the stronger the current the greater the deflection. He made the effect more sen sitive by winding the wire many times in a coil around the magnetic needle. In this way he invented the first gal vanometer. 2 8 6
|
