Biographical encyclopedia
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456 [694] OTTO
CROOKES [695] He also made some observations on silicon-containing organic compounds, which he did not follow up but which were to be taken further, very fruitfully, by Kipping [930]. In 1892 he headed the meeting at Geneva that systematized or ganic chemical nomenclature. [694] OTTO, Nikolaus August German inventor Born: Holzhausen, Hesse-Nassau, June 10, 1832 Died: Cologne, January 26, 1891 After the invention of the Lenoir [635] engine a number of attempts were made to increase its efficiency. In 1862 theoret ical studies were published that showed explosions within the cylinder combined with four movements of the piston would prove adequately efficient. As the piston moved outward (first movement), a mixture of gas and air would be drawn into the cylinder. As the piston moved in (second movement) the mixture would be compressed. At the height of compression a spark would set off the explosion, driving the piston out (the third movement and the power stroke). When the piston moved in (the fourth movement), the exhaust gases would be forced out. The cycle would then be repeated. In 1876 Otto, a traveling salesman, who was the son of a farmer and who chanced upon a newspaper account of Lenoir’s discovery, was the first to build such an internal combustion engine and the four-stroke cycle is sometimes called the Otto cycle in his honor. Otto pat ented it in 1877 and formed a company that sold 35,000 such engines in a few years, and by 1890 the Otto engines were virtually the only internal combus tion engines used. It was the Otto engine that made possible the automobile and the airplane. [695] CROOKES, Sir William English physicist Bom: London, June 17, 1832 Died: London, April 4, 1919 In 1848 Crookes, eldest of the sixteen children of a tailor who had enriched himself by shrewd real estate invest ments, entered the Royal College of Chemistry and studied under A. W. von Hofmann [604], but despite this and de spite the fact that his first publication, in 1851, concerned organic compounds, he wandered away from organic chemistry with the encouragement of Faraday [474],
Eventually inheriting his father’s for tune, he was able to settle down serenely to a life of research and to a marriage that yielded ten children. The work of Kirchhoff [648] interested him greatly and he threw himself into the study of spectroscopy. The organic compounds he had dealt with were selenium-containing ones, and the ores from which he obtained the selenium were still in his possession. He studied them spectroscopically and in 1861 dis covered a beautiful green line in their spectra that fitted no known element. It was a new element therefore and he named it thallium from a Greek word meaning “green twig.” He was elected to the Royal Society in 1863 in conse quence. In investigating the atomic weight of thallium, Crookes made delicate weigh ings in vacuum in order to avoid errors introduced by the buoyant effect of the atmosphere. However, the balance showed erratic swayings at times and Crookes began to study the behavior of objects in vacuum. In 1875 he devised the radiometer, a little affair consisting of a set of pivoted vanes in a vacuum. One side of each vane was blackened to absorb heat and the other side was shiny to reflect it. In the presence of sunlight or other radiation, the vanes turned steadily. This was not due to solar radia tion itself for if the container was evac uated particularly well, the motion ceased though the radiation was as strong as ever. It seemed then that the effect was due to air molecules in the partial vacuum that rebounded from the heated side of each vane more strongly than from the shiny side, thus “kicking” it around. Though never more than a 4 5 7
[695] CROOKES
CROOKES [695] toy, the radiometer did provide a new piece of evidence in favor of the kinetic theory of gases and Maxwell [692] him self worked out the theory of radiometer action on that basis. Crookes’s new interest in vacuums led him naturally into the study of the radia tion and luminescence that appeared about the cathode (that is, the negative electrode) when it was placed under strong electric potential within an evac uated Geissler [583] tube. Crookes de vised methods for producing still better vacuums and by 1875 had devised an improved vacuum tube in which the air pressure was but 1/75,000 that in a Geissler tube and in which the radiation could be more efficiently studied. This has been called a Crookes tube ever since. (The new techniques for produc ing a vacuum made Edison’s [788] in candescent bulb practical for mass pro duction.) Crookes’s careful studies in the 1870s independently covered the ground earlier investigated by Pliicker [521] and Hittorf [649], but Crookes presented the results much more systematically and dramati cally. He showed that the radiation from the cathode, which Goldstein [811] had just named cathode rays, traveled in straight lines. Small objects placed in the path of the radiation cast a sharp shadow in the fluorescence at the end of the tube. Crookes also showed the radia tion could turn a small wheel, when it struck one side. All this could be ex plained by supposing the cathode rays to be electromagnetic (after all, the elec tromagnetic radiation of the sun indi rectly turned the radiometer), but one experiment remained. Crookes went on to show that the radiation could be deflected by a magnet. He was convinced therefore that he was dealing with charged particles speeding along in straight lines and not with electromag netic radiation. Crookes spoke of these charged parti cles as a fourth state of matter, or an ul tra-gas as far beyond the ordinary gas in rarefaction and intangibility as that ordi nary gas was beyond the liquid. At the time, this notion was greeted with reser vation and even hostility by other scien tists, but in less than two decades J. J. Thomson [869] was to show Crookes to be entirely right, and a new word, “elec tron”—invented by Stoney [664]—was to make its appearance on the scientific scene.
Crookes on several occasions nearly stumbled on great discoveries that were eventually made by others. More than once he fogged photographic plates dur ing the running of his Crookes tube even though those plates were enclosed in their containers. However, he missed the connection and it was Roentgen [774] a decade or so later who, also using a Crookes tube, was to discover X rays and initiate the Second Scientific Revolu tion. Again, Crookes had views that nearly brought him to the recognition of isotopes but he fell just short, and that great advance was left to Soddy [1052], Unlike men such as Kelvin [652], Crookes maintained his creative energies and did not let the rapid pace of advanc ing science leave him behind. The dis covery of radioactivity by Becquerel [834] inspired Crookes to investigate on his own into the mysterious uranium. In 1900 he found that a solution of ura nium salt could be treated in such a way as to precipitate a small quantity of the material, and that this small quantity contained most of the radioactivity. The uranium left in solution was almost inac tive. For a while Crookes maintained that it was not the uranium after all that was radioactive but some impurity. He was both right and wrong in this. The deactivated uranium regained its ac tivity, as Becquerel pointed out, and so it seemed that uranium in giving off its ra diations was converted to something else that was much more radioactive than the parent uranium. This new product could be separated from uranium, leaving the parent much less radioactive, but still by no means entirely nonradioactive. This was the first indication that radio activity involved the change of one ele ment into another, something that Kel vin strenuously denied in his own very conservative old age. 458 [696] CLARK
WUNDT [697] In 1903 Crookes showed that the par ticles of alpha rays (one variety of radia tion from radioactive substances) caused zinc sulfide to luminesce and that under the miscroscope this luminescence con sisted of numerous individual flashes. It was easy to see that each flash was the result of the impact of a single alpha particle. This spinthariscope (Greek for “spark viewer”), which Crookes had thus invented, was later used most effec tively by Rutherford [814] in particularly startling experiments. Crookes was knighted in 1897, and was president of the Royal Society from 1913 to 1915. He was one of the occasional impor tant scientists who grow interested in psychic research and spiritualism and was, every once in a while, overgullible in his approach to mediums. [696] CLARK, Alvan Graham American astronomer Born: Fall River, Massachusetts, July 10, 1832 Died: Cambridge, Massachusetts, June 9, 1897 Clark was primarily a lens grinder and maker of astronomical instruments, in which profession his father had preceded him. On January 31, 1862, he was at his father’s optical shop, testing a new 18-inch lens they had ground, and he pointed it at Sirius. Bessel’s [439] obser vation that Sirius had a small wavy movement had led astronomers to as sume that it had a massive dark compan ion. Clark, however, saw a tiny spot of light near Sirius, which on further study proved to be its companion and not dark at all. For this he received a medal from the French Academy of Sciences. It was not until well after Clark’s death that the most interesting aspect of the companion of Sirius was uncovered, for in 1914 W. S. Adams [1045] showed the companion to be a new kind of star of a nature that would not have seemed possible in Clark’s generation. The telescopes produced by Clark’s firm were world famous. In 1859 Clark went to England to demonstrate his tele scopes and they came to be used in Europe as well as in the United States. Hall [681] discovered the satellites of Mars through a Clark telescope and Bar nard [883] discovered Jupiter’s fifth sat ellite through another. In 1897 shortly before his death Clark crowned his life- work by supervising the construction of the 40-inch Yerkes telescope. This was and is the largest refracting telescope in existence. All larger telescopes built be fore or since have been reflectors, for large mirrors (used in reflectors) are easier to build and involve fewer me chanical difficulties than the large lenses used in refractors. [697] WUNDT, Wilhelm Max (voont) German psychologist
August 16, 1832 Died: Grossbathen, near Leipzig, Saxony, August 31, 1920 Wundt, the son of a minister, having gained both a Ph.D. and an M.D. joined the faculty of the University of Heidel berg in 1854, and spent some time work ing with J. Müller [522] and Du Bois- Reymond [611]. He grew interested in psychology, which he interpreted in the fight of the work of Ernst Weber [492] and Fechner [520].
It seemed to him that there were facets of human behavior that could be measured, in particular, the manner in which man absorbed sense impressions. The work of Helmholtz [631] on vision and hearing seemed an important case in point, and Wundt was enthusiastic enough to initiate, in 1862, the first uni versity course ever given in experimental psychology. In 1875 he transferred to the Univer sity of Leipzig, and there in 1879 he es tablished the first laboratory to be de voted entirely to experimental psychol ogy. He also founded, in 1881, the first journal to be devoted to the subject. 459 [698] CAILLETET SACHS
[698] CAILLETET, Louis Paul (ka- yuh-tay') French physicist Born: Chatillon-sur-Seine, Côte d’Or, September 21, 1832 Died: Paris, January 5, 1913 Cailletet was the son of a metallurgist and as a young man worked in his fa ther’s iron foundry. In 1870 he grew in terested in the gas laws and made careful measurements to see just how the actual behavior of gases deviated from that predicted by those laws, a matter which Van der Waals [726] was to treat in de tail. From that he grew interested in the liquefaction of gases. He extended Andrews’s [580] work and suggested that all gases had a critical temperature. To liquefy gases, he there fore made use of the Joule [613]-Thom- son [652] effect. He began by compress ing a gas and cooling it as much as he could. He then allowed it to expand, and in expanding, it would cool drastically. In 1877 Cailletet managed in this way to produce small quantities of liquid oxy gen, nitrogen, and carbon monoxide. At the same time Pictet [783], working in dependently, achieved a similar success. Cailletet was elected to the Academy of Sciences in 1884 and was made an officer in the Legion of Honor in 1889, as a result of his achievement. The Cailletet-Pictet method is difficult to apply to hydrogen because the Joule- Thomson effect does not work for hydro gen except at temperatures below —83°C. Dewar [759] succeeded in liq uefying hydrogen because he cooled his hydrogen gas with liquid nitrogen to reach a very low temperature first, and then began making use of the Joule- Thomson effect. [699] SACHS, Julius von (zahks) German botanist Born: Breslau, Silesia (now Wroclaw, Poland), October 2, 1832
May 29, 1897 Sachs, the son of an engraver, was orphaned at seventeen and was left with out money, but he managed to get an edu cation and began his professional career as assistant to Purkinje [452], Purkinje rec ognized his talent and befriended him. Sachs then obtained his Ph.D. at Prague in 1856, became a professor of botany at the University of Freiburg-im-Breisgau, and later established a laboratory at Wurzburg. He showed that plants, like animals, respond to their environment and docu mented plant tropisms (the manner in which their parts move in response to light, water, gravity, and so on). He also worked out the process of plant tran spiration, whereby water travels from the roots, up the stem, and (in vapor form) out the leaves. He was particularly interested in prob lems of plant nutrition and his most im portant discoveries in this connection in volved the green pigment, chlorophyll, which had been discovered a generation earlier by Pelletier [454] and a co worker. Because leaves and other plant parts appear uniformly green, it might seem that chlorophyll is evenly spread through out the plant. Sachs showed that this was not so. In 1865 he published a comprehensive botanical treatise proving that chlorophyll was confined to certain discrete bodies within the cell, which later received the name of chloroplast. It is within the chloroplast that chlorophyll is formed and that starch grains first ap pear when the leaf is exposed to light. This was the final broad brushstroke in the picture of plant nutrition. Helmont [175], Priestley [312], and Ingenhousz [306] had, among them, showed that green plants convert carbon dioxide and water into tissue components, liberating oxygen in the process. Now Sachs showed that the process is catalyzed by chlorophyll, within the chloroplasts, in the presence of light. He also showed that, in addition to this, plants respired as animals do, consuming oxygen and producing carbon dioxide, though it is the reverse photosynthetic effect that predominates. The working out of the details of the
[700] NORDENSKIÖLD BERT
process had to wait, however, nearly a century for the work with radioisotopes by Calvin [1361] and others. [700] NORDENSKIOLD, Nils Adolf Erik (noor'den-shuld') Swedish geologist
November 18, 1832 Died: Dalbyô, Sweden, August 12, 1901 Nordenskiold was of an aristocratic Swedish family although he was born in Finland, which had once been part of Sweden but which at the time of his birth was part of Russia. He was edu cated at the University of Helsinki, but his liberal views got him in trouble with the Russian authorities and in 1858 he left for Sweden, which remained his home thereafter. He is most famous for his polar explo rations and, in particular, for a voyage he made in 1878-1879, on the Vega, during the course of which he made his way along the Arctic coast of Siberia from Norway to Alaska (albeit he was icebound for months at a time) then re turned to Europe by way of the Pacific Ocean, the Indian Ocean, and the Suez Canal. He was the first person to navi gate the so-called Northeast Passage and the first person to circumnavigate Asia. Nordenskiold was the first to conduct polar exploration with strict attention to the gathering of scientific data. He pub lished five volumes of material on every aspect of the polar regions of the earth as a result of his Vega voyage. [701] WAAGE, Peter (voh'guh) Norwegian chemist Born: Flekkefjord, June 29, 1833 Died: Oslo, January 13, 1900 Waage, the son of a ship’s captain, was educated at the University of Chris tiania (Oslo) and became a professor of chemistry there in 1862. Waage is known entirely because of his association with Guldberg [721], his brother-in-law, in formulating the law of mass action. Outside science, he was deeply in volved in the temperance movement. [702] BERT, Paul (bair) French physiologist
17, 1833 Died: Hanoi, Indochina (now Vietnam), November 11, 1886 Bert, the son of a lawyer, was a stu dent of Bernard [578] in 1868. He had a wide range of interests and although he is chiefly known for his work in physiol ogy, obtaining his M.D. in Paris in 1863, he was also educated in law and en gineering and was involved in politics as well.
He became professor of physiology at the University of Bordeaux in 1866, and in 1869 he joined the physiology depart ment at the Sorbonne. In those years men were beginning to dig deep to tun nel under rivers or to lay the foundations for bridges. To do so they had to use compressed air to keep out the water and many workers came down with the agonizing and sometimes fatal condition known as bends. Bert, studying the effect of compressed air on the body, realized that nitrogen under pressure dissolved in tissue fluids more easily and that when the high pressure of the compressed air was released too rapidly as the workers came up to sea level, the nitrogen bub bled out into the blood and tissues. This was the cause of bends, and to prevent it, it was only necessary to lower the air pressure by slow stages. Bert published his views in 1878 and work with com pressed air became safe. Bert served as an ultralibéral member of the French Chamber of Deputies from 1874 to 1886 and in 1881-1882 was a member of the cabinet as minister of public instruction. He fought for free public education and for the separation of church and state. In 1886, he was appointed governor general of Indochina and went to his death, for dysentery killed him a few months after his arrival there. Download 17.33 Mb. Do'stlaringiz bilan baham: 
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