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381 [578] BERNARD
BERNARD [578] mals in which he had artificially created fistulas—openings connecting the diges tive tract with the outside of the body. Some of the important early studies on digestion had arisen from the work of Beaumont [444] on a man with an acci dentally caused fistula and now Bernard decided not to wait upon accident. (For this he was roundly criticized by the an- tivivisectionists of the day. Among these were Bernard’s wife and two daughters. His wife, whom he had in any case mar ried only for her money, was sincere enough in her anger at him to contribute large sums to antivivisection societies and to obtain a legal separation in 1870.)
He was able to show that the stomach was not the entire seat of digestion as, until his time, it had been assumed to be. Instead, although some digestion did take place there, it was but the anteroom of the process. By introducing foodstuffs directly into the initial portion of the small intestine, where the juices of a gland called the pancreas would impinge upon it, he showed that the main processes of digestion took place through the length of the small intestine and that the pancreatic secretions were an impor tant agent of digestion, breaking down fat molecules in particular. In 1851 Bernard discovered that cer tain nerves governed the dilatation of blood vessels and others their con striction. In this way the body was able to control the distribution of heat within itself. On hot days, when heat had to be radiated away efficiently, the blood ves sels of the skin were dilated, while on cold days, when heat must be conserved, they were constricted. It is for this rea son that individuals flush with heat and turn pale with cold. He also showed that it was the red corpuscles of the blood that transported oxygen from lungs to tissues.
To Bernard this was an example of body mechanisms acting as though they were striving to maintain a constant inner environment despite the changing qualities of the outer environment. To do so, the various organs of the body had to be under a tight and integrated central control. This is the view now ac cepted, but in the 1850s, when Bernard advanced it, it was in opposition to a trend of thought that, at the time, would have it that the various organs per formed their functions in relative isola tion. (As a matter of fact the early pro ponents of the cell theory, for instance Schwann [563], were sufficiently in fluenced by “nature philosophy” to sup pose that even the individual cells had an almost independent life of their own.) Bernard went on to show that this careful balance within the body extended to chemical reactions and not merely to physical ones. In 1856 he discovered the presence of a starchlike substance in mammalian liver, which he called glyco gen. He showed that it was built up out of blood sugar and acted as a reserve store of carbohydrate that could be bro ken down to sugar again when necessary. Whether glycogen is built up or broken down depends on the exact state of the body, the energy requirements of the various tissues, the food supply in the in testines, and so on, but the net result is that the glycogen balance is so maneu vered that the sugar content in the blood remains steady. This was the first clear indication that the animal body did not merely tear down complicated molecules into simple ones (catabolism). It, like the plant or ganism, could be constructive also, build ing up a large molecule like glycogen out of small ones like sugar (anabolism). Of course the body’s equilibrium could be upset if pushed too hard. Bernard showed that the poisonous action of car bon monoxide lay in its ability to dis place oxygen in its combination with he moglobin. The body could not counter this quickly enough to prevent death by oxygen starvation. This was the first suc cessful explanation of the specific man ner in which a drug acted upon the body. Bernard was not receptive to Darwin’s [554] theory of evolution. French biolo gists generally, even the great Pasteur [642], were more hostile to Darwinism than were those elsewhere in Europe and 382 [579] STAS
ANDREWS [580] America. This was partly because of the still-remembered teachings of the two great Frenchmen of half a century ear lier, Lamarck [336] and Cuvier [396]. In life, Bernard was elected a member of the super-select French Academy in 1869 and served in the French senate under Napoleon III. He escaped from Paris at the last moment when the Prus sians were encircling it in 1870. When he died of kidney disease he was given a public funeral, the first scientist upon whom France had bestowed this honor. [579] STAS, Jean Servais Belgian chemist Born: Louvain (Leuven), August 21, 1813 Died: Brussels, December 13, 1891
Stas, the son of a shoemaker, was an other one of those who obtained a medi cal degree but never practiced. He was a professor of chemistry at the University of Brussels and was probably the most skillful chemical analyst of the nine teenth century. Interest in the atomic weights had been sparked by Prout [440] and his famous hypothesis of a half cen tury earlier, Cannizzaro [668] had fur thered its importance. Stas had begun work in this direction as a student under Dumas [514], with whom he established the atomic weight of carbon as 12, not 6 as others had persistently claimed. For a decade centered on 1860 Stas worked assiduously in determining atomic weights more accurately than had ever been done before, even by Berzelius [425]. Stas used oxygen = 16 as an atomic weight standard and this became universal practice for a century thereaf ter. No further advance was to be made until the work of Richards [968] a half century later. Stas’s work showed beyond any doubt that the atomic weight of some elements was far removed from integral values and this seemed to be the deathblow to Prout’s hypothesis that all atoms except hydrogen were conglomerations of hy drogen atoms and therefore had integral atomic weights. However, fifty years later, Soddy’s [1052] work was to open this seemingly closed question once more, on a much more sophisticated level. In 1865 Stas accepted a government position as Commissioner of the Mint, but did not keep it long. His liberal views were too much for the conser vative Belgian government, under Leo pold II, to accept, and he resigned in 1872.
[580] ANDREWS, Thomas Irish physical chemist Born: Belfast, December 19, 1813
Died: Belfast, November 26, 1885
Andrews, the son of a linen merchant, attended Glasgow University, then stud ied under Dumas [514] in Paris and finally went on to receive his medical de gree from the University of Edinburgh in 1835. He practiced medicine at Belfast and also taught chemistry. In 1845 he became a professor of chemistry at Northern College in Belfast, a post he held till his retirement in 1879. Andrews identified ozone, discovered earlier by Schonbein [510] as a form of oxygen but could not determine its con stitution. His most important work was done in the liquefaction of gases. Faraday [474] had pioneered in the field, liquefying certain gases by placing them under pressure. Some, such as oxygen, nitro gen, and hydrogen, had resisted liquefac tion despite all the pressure that could be placed upon them. By 1845 these nonliq uefying gases were called permanent gases and there was serious suspicion that they might be incapable of liquefac tion.
Andrews worked with carbon dioxide, a gas that can be liquefied at ordinary room temperature by pressure alone. Working with a sample of liquid carbon dioxide under pressure, he slowly raised the temperature, noting the manner in which the pressure had to be increased to keep the carbon dioxide liquid. As he 383 [581] PARKES
GEISSLER [583] did so, however, the boundary line be tween liquid carbon dioxide and the car bon dioxide vapor above grew fainter and at 31°C it disappeared. The carbon dioxide was all gas and no amount of pressure that Andrews could exert would change it to liquid again. Andrews therefore suggested that for every gas there was a temperature above which pressure alone could not liquefy it. This temperature he called the critical point. (The Russian chemist Mendeléev [705] had made much the same observa tion two years earlier while a student in Germany, but his report had gone unno ticed.) This was a crucial discovery for it pointed the way toward the liquefaction of the permanent gases by demonstrating the necessity of dropping the tempera ture below the critical point before exert ing pressure. This new view led within half a century to the work of Dewar [759] and Kamerlingh-Onnes [843] and the liquefaction of all known gases. [581] PARKES, Alexander English chemist Born: Birmingham, December 29, 1813
Died: London, June 29, 1890 Parkes’s patents included one, in 1841, for waterproofing fabrics by coating them with rubber and another, in 1843, for an electrometallurgical process that was particularly suited to electroplating delicate objects. He is supposed to have presented to Prince Albert (Queen Vic toria’s husband, one member of royalty who was consistently interested in sci ence) a silverplated spider web. In the early 1850s, Parkes discovered that pyroxylin (partly nitrated cellulose), if dissolved in alcohol and ether in which camphor has also been dissolved, will produce a hard solid upon evaporation, which will soften and become malleable when heated. He found no way of suc cessfully marketing this substance, how ever, and it was left to Hyatt [728], fifteen years later, to place it in the pub lic eye.
Nevertheless, successfully applied or not, Parkes had discovered the first plas tic. [582] FREMY, Edmond (fray-meeO French chemist Born: Versailles, February 28, 1814
Died: Paris, February 2, 1894 Fremy began his chemistry career in 1831 as assistant to Gay-Lussac [420], and gained his first professorial post in 1846. He succeeded Gay-Lussac in his post at the Museum of Natural History when Gay-Lussac died in 1850, and at the retirement of Chevreul [448] in 1879 became the director of the museum. He worked on a variety of chemical problems and produced synthetic rubies by heating aluminum oxide with potas sium chromate and barium fluoride. He is best remembered today, perhaps, for his work with fluorine compounds. He discovered a number of such com pounds, including hydrogen fluoride. Chemists had long known there was an element in the fluorides that resembled chlorine but was even more active. It was so active, however, that it could not be torn away from the other elements with which it had combined so that it was not produced as a free element. Fremy made a stubborn attempt, but failed. In this, however, he laid the groundwork for Moissan [831], who suc ceeded.
[583] GEISSLER, Heinrich (gisefler) German inventor Born: Igelshieb, Saxe-Meiningen, May 26, 1814 Died: Bonn, Rhenish Prussia, January 24, 1879 Geissler, the son of a burgomaster, was a skillful glassblower and in 1852 opened a shop in Bonn for the manufac ture and sale of scientific instruments. His chief fame came in connection with vacuum production. Two centuries earlier Guericke [189]
[584] DAUBRÉE
ANGSTROM [585] had invented the first air pump. With this he could produce a vacuum by pumping air out of a vessel, and with such a vacuum physicists could experi ment to their heart’s content. Torricelli [192] had created a better vacuum over a column of mercury than an air pump of the time could produce. This re mained merely a curiosity, however, for it was a vacuum within a closed con tainer and was not therefore available for experimentation. In 1855 Geissler took advantage of Torricelli’s discovery to devise an air pump without moving mechanical parts. He moved a column of mercury up and down. The vacuum above the column could be used to suck out the air within an enclosed vessel, little by little, until the vacuum within the vessel approached that above the mercury. In this way he evacuated chambers more thoroughly than anyone ever had before. Tubes so evacuated were named Geissler tubes by Geissler’s friend Pliicker [521]. Geissler tubes made possible an impor tant advance in the study of electricity and of the atom. Physicists had been at tempting to send electric discharges through evacuated vessels, and Faraday [474] had noted that a fluorescence was produced as a result. However, the vac uum used by Faraday was not good enough to allow much work to be done. With the Geissler tubes that was changed and a course of research was initiated that led to the discovery of the electron by J. J. Thomson [869] four decades later.
[584] DAUBRÉE, Gabriel Auguste (doh-brayO French geologist
Daubrée studied at the École Poly technique and became a qualified mining engineer in 1834. In 1861 he was ap pointed professor of geology at the Paris Museum of Natural History. He toured western Europe and Algeria as well. He rose in his profession until, in 1867, he was appointed inspector general of mines, keeping that position till he re tired in 1886. He applied experimental methods to the study of minerals, investigating methods of origin and formation. He also studied and classified meteorites, building a collection of them. He was struck by the fact that a number of them were almost pure nickel-iron. Since it was well known that the center of the earth was high-density, he suggested in 1866 that nickel-iron was a common component of planetary structure and that earth’s core might be formed of that alloy. This suggestion is now accepted as highly probable by geologists generally. [585] ANGSTROM, Anders Jonas (ohng'strum) Swedish physicist Born: Logdo, Medelpad, August 13, 1814 Died: Uppsala, June 21, 1874 Angstrom, the son of a lumber mill chaplain, was educated at the University of Uppsala, where he obtained his Ph.D. in 1839 and where he spent his life teaching physics and astronomy, achiev ing his professorship in 1858. He had anticipated Kirchhoff [648] in seeing that a cool gas absorbs just those wavelengths of light it emits when it is hot. Conse quently when Kirchhoff developed this in detail and established spectroscopy, Angstrom was not slow to apply it to the heavens. In 1861 he began to inspect the solar spectrum in this new light—as Huggins [646] was doing independently in En gland—and, in 1862, announced the dis covery of hydrogen in the sun. He soon discovered other elements as well, and in 1868 published a map of the spectrum, locating the wavelength of about a thou sand lines with great care. In 1867 he had also been the first to study the spec trum of the aurora borealis. He did not use an arbitrary measure as Kirchhoff had done, but actually mea sured the wavelengths in units equal to a ten billionth of a meter. This unit was
[586] KIRKWOOD
MAYER [587] officially named the Angstrom unit in 1905. Angstrom was elected to the Royal So ciety in 1870 and received the Rumford medal (the first to a Swede) in 1872. [586] KIRKWOOD, Daniel American astronomer Born: Harford County, Maryland, September 27, 1814 Died: Riverside, California, June 11, 1895 Kirkwood, the son of a farmer, had little formal education in his early years but learned mathematics on his own and finally served as professor of mathe matics at Delaware College, then at Indiana University, and finally lectured at Stanford University. He turned his attention to the as teroids, knowledge of which had been initiated with the work of Piazzi [341] and Olbers [372] a half century before, and was the first to do more than simply discover new ones. In 1857 he proved that the orbits of those already known (about fifty at that time) were not evenly distributed about an average orbit. Instead there were regions that were free of asteroids. He showed in 1866, by which time the number of known asteroids had risen to eighty- seven, that if asteroids did exist in those Kirkwood gaps (as they are now known) they would have annual periods of revolution that would be in simple ratio to that of Jupiter. The perturba tions of Jupiter would slowly build up, forcing the asteroids into an orbit closer to or farther from the sun, and the gap would remain a gap. Kirkwood was further able to show that there were similar gaps in Saturn’s rings (which was why they were rings, rather than a ring) owing to the perturb ing effect of Saturn’s satellites. If there were ring particles in Cassini’s [209] gap, for instance, they would circle Saturn in just half the period that Mimas, its in nermost satellite, did. Mimas’s perturba tions would force the ring particles out of that position, renewing the gap that divided the ring into two major sections. Newton’s [231] theory of gravitation thus met another test in explaining the fine details of the structure of the solar system (although in 1980 the Voyager I probe showed the structure of the ring to be too complex to be easily explained by such “resonance” considerations alone). Kirkwood also maintained that Mer cury probably showed a single face to the sun at all times because of tidal effects. Schiaparelli [714] was to report having observed this and it was not till the 1960s that the true rotational period of Mercury (only two-thirds its period of revolution) was to be demonstrated. Asteroid $1578 has been named in Kirkwood’s honor. [587] MAYER, Julius Robert (m/er) German physicist Born: Heilbronn, Württemberg, November 25, 1814 Died: Heilbronn, March 20, 1878
Originally trained as a physician at the University of Tübingen, Mayer, the son of an apothecary, was not a particularly good scholar. He obtained his medical degree in 1838, although the year before he had been expelled for his liberal views. He did not enjoy medical practice. He served as ship’s doctor under con ditions which gave him little to do but think; and about 1840, during a trip to Java, he began to interest himself in physics, while considering the problem of animal heat. In 1842 he presented a figure for the mechanical equivalent of heat, based on an experiment in which a horse powered a mechanism that stirred paper pulp in a caldron. He compared the work done by the horse with the temperature rise in the pulps. His experiments were not as detailed and careful as those by Joule [613] but Mayer saw their significance and clearly presented his belief in the conservation of energy before either Joule or Helmholtz [631] did. He had some difficulty getting his paper on the subject published but Lie big [532] finally accepted it for the im Download 17.33 Mb. Do'stlaringiz bilan baham: 
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