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[931] BAEKELAND HALL [933]
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[931] BAEKELAND HALL
an independent consultant and invented a type of photographic paper that could be developed under artificial light. It was the first commercially successful photographic paper and he sold it to Eastman-Kodak for a million dollars. (Baekeland had planned to ask $50,000 and to go down to $25,000 if necessary, but fortunately for him Eastman [852] spoke first.) After a short visit to Germany in 1900 Baekeland plunged into a project to evolve a synthetic substitute for shellac in the laboratory he had built in his home in Yonkers, New York. For the purpose he began to investigate those or ganic reactions that produced gummy, tarlike insoluble residues that ruined glassware and seemed to have no other use. It was Baekeland’s intention to form such a residue by reacting phenol and formaldehyde, then find a solvent that would dissolve it. That solution would then be his shellac substitute. He formed the residue easily enough but could find no solvent. Suddenly it occurred to him to look at matters backward. If the residue was hard and resistant to solvents, couldn’t that be a useful combination of proper ties in itself? He began to concentrate on forming the resinous mass more efficiently and making it still harder and tougher. By using the proper heat and pressure, he obtained a liquid that so lidified and took the shape of the con tainer it was in. Once solid, it was hard, water-resistant, solvent-resistant, and an electrical insulator. Moreover, it could be cut with a knife and easily machined. He waited for several years while he continued to experiment and in 1909 he announced the existence of the substance he named Bakelite after himself. It was not the first plastic; Hyatt [728] and his celluloid deserve that credit. However, Bakelite was the first of the “thermoset ting plastics” (one that once set would not soften under heat) and is still one of the most useful a half century later. It was Bakelite that sparked the modem development of plastics. In 1924 Baekeland served as president of the American Chemical Society. [932] CANNON, Annie Jump American astronomer
ber 11, 1863 Died: Cambridge, Massachusetts, April 13, 1941 Cannon was the daughter of a state senator. She was educated at Wellesley College, graduating in 1884, then re turned in 1894 for additional instruction in astronomy. She went on to study it still further at Radcliffe, perhaps at the suggestion of E. C. Pickering [784], In 1896 she joined the staff at Harvard Ob servatory and remained there the rest of her life. She was particularly interested in the task of classifying the large numbers of stellar spectra that had been photo graphed, and developed a classification system that Harvard used ever since. She showed that with very few exceptions the spectra could be arranged into a con tinuous series. Her work formed the basis of the Henry Draper [723] Cata
the spectral classification of 225,300 stars brighter than ninth or tenth magni tude.
[933] HALL, Charles Martin American chemist Born: Thompson, Ohio, Decem ber 6, 1863 Died: Daytona Beach, Florida, December 27, 1914 Hall, the son of a minister, was edu cated at Oberlin, from which he gradu ated in 1885. He, like Perkin [734], was intensely interested in chemistry as a youngster and, again like Perkin, was stimulated by a chance remark of his teacher into making the great discovery of his life. Hall’s teacher stated that any one discovering a cheap way of making aluminum would grow rich and famous. Hall took him at his word, made the dis covery, and grew rich and famous. Aluminum, a very common constit uent of the earth’s crust, in metallic form is light, strong, and a good conductor of
[933] HALL
WIEN [934] electricity. It has any number of possible uses, but the one trouble was that for over half a century after its discovery there seemed no way of isolating it from its compounds in a cheap and practical way. The closest approach had been that of Sainte-Claire Deville [603] in 1855 and even then aluminum remained a semiprecious metal. Napoleon III of France had his cutlery and his baby’s rattle made out of aluminum, and the top of the Washington Monument (which was dedicated in 1885) is a slab of the then expensive metal. In 1886 Hall, at twenty-two, went to work in his home lab (as Perkin had done a generation earlier) and, using homemade batteries, devised a method of making aluminum by electrolysis after the fashion of Davy [421] and did it only eight months after graduation from college. The key discovery was that of dissolving an aluminum oxide in a mol ten mineral called cryolite and using car bon electrodes. That same year, working independently, Heroult [925], in France, devised the same method. It is therefore usually called the Hall-Heroult process. On February 23, 1886, Hall was able to show his teacher the little globules of aluminum he had formed. These glob ules are still reverently preserved by the Aluminum Company of America, for, indeed, the Hall-Heroult process was the foundation of the huge aluminum indus try of today. Within seven years, the price of aluminum dropped from $5 a pound to 700 a pound. By 1914 it was down to 180 a pound. Aluminum now is second only to steel (which, thanks to Hadfield [892], devel oped astonishing new properties of its own) as a construction metal, and where lightness is important, it is first. It is difficult to see how practical aircraft could ever have been developed without a plentiful supply of cheap aluminum. Its uses are numberless, from canoes to house siding to paint to power lines to storm windows. Goldschmidt [909] even managed to use it in a high-temperature device. In 1911 Hall, very appropriately, re ceived the Perkin medal. On his death he left no less than five million dollars to his old alma mater, Oberlin.
[934] WIEN, Wilhelm (veen) German physicist Born: Gaffken, East Prussia (now Primorsk, USSR), January 13, 1864
30, 1928 Wien was the son of a landowner, and though this placed him in a position to afford a good education, it did introduce difficulties, for between 1886 and 1890 he had to interrupt his studies to run the family estate during the sickness of his father. He had the good fortune in his student years to work as assistant to Helmholtz [631], under whom he ob tained his Ph.D. in 1886. In the 1890s Wien began to work with the problem of radiation. A generation earlier Kirchhoff [648] had worked out his theory that hot bodies radiate those wavelengths that they absorb when cold. It followed, then, that a body that ab sorbed all wavelengths and was therefore perfectly black (a “black body”) would radiate all wavelengths when heated. Naturally, as Prévost [356] had pointed out a century before, the amount of radi ation rose with temperature. About fifteen years earlier Stefan [715] had used thermodynamics to show exactly how the amount rose. Wien was interested in the nature as well as the amount of the radiation. He and his colleagues experimented with the practical equivalent of a black body, an enclosed, heated chamber with a small hole in it. Any light of whatever wave length entering the hole was not reflected but was absorbed within, so out of the hole should stream black-body radiation of all wavelengths. Through observation of the nature of the radiation emitted and through ther modynamic reasoning, Wien in 1893 showed that the wavelengths of the radi ation emitted reach a peak at some inter mediate level. The wavelength at this
[934] WIEN
NERNST [936] peak varies inversely with temperature. Therefore, as temperature rises, the pre dominant color shifts toward the blue end of the spectrum. Moderately hot bodies radiate chiefly in the infrared, to which we are visually insensitive, but as the temperature rises, the peak shifts to ward the visible red and the heated body begins to glow. As temperature continues to rise, the glow is first a dull red, then a bright red, then yellow-white and finally blue-white. Extremely hot stars radiate mostly in the ultraviolet to which again we are visually insensitive, and superhot objects such as the sun’s corona actually radiate in the X-ray region. This shift of peak wavelength with temperature is called Wien’s displacement law. Wien also tried to evolve an equation that would describe the distribution of all wavelengths in black-body radiation for all temperatures, and not just for the peak wavelength. He had to juggle mat ters a bit but worked out an equation that would fit the observed distribution of the short wavelength (high- frequency) radiation. It would not, how ever, fit the long wavelength (low- frequency) radiation. On the other hand Rayleigh [760] evolved an equation that fit the long wavelengths and not the short. It was as a result of these short comings that Planck [887] was lured at the end of the decade into devising the quantum theory, which placed the entire matter of energy and, indeed, of physics generally, in a new and better light. Wien then grew interested in X rays and cathode rays, which in the second half of the 1890s were setting the world of physics by its ears and were inau gurating the Second Scientific Revolu tion. Although his work here was good (he deflected Goldstein’s [811] canal rays with a magnet, for instance, and showed them to be positively charged), he was outclassed by others. In 1900 he succeeded Roentgen [774] at the University of Wurzburg and in 1920 succeeded him again at the Univer sity of Munich. In 1911, for his work on black-body radiaton, he received the Nobel Prize in physics. [935] MINKOWSKI, Hermann (ming- kufskee) Russian-German mathematician Born: Alexotas, Russia, June 22, 1864
Died: Göttingen, Germany, Janu ary 12, 1909 Minkowski was bom of German par ents who returned to Germany in 1872. He earned his Ph.D. at the University of Königsberg in 1885. He taught there for a few years, then went to the University of Zürich, and finally to Göttingen. When Einstein’s [1064] special theory of relativity was first published in 1905, Minkowski was extraordinarily inter ested. (Einstein had been one of his pu pils.) Einstein’s paper made it clear that ordinary three-dimensional geometry was not adequate to describe the universe, but it was Minkowski who placed a for mal geometric interpretation upon rela tivity.
He showed in a book, Time and Space, published in 1907, that relativity made it necessary to take time into ac count as a kind of fourth dimension (treated, mathematically, somewhat differently from the three spatial dimen sions). Neither space nor time has exis tence separately, in his view, so that the universe consists of a fused “space-time.” Einstein adopted this notion and went on to develop it to still greater heights in his general theory of relativity nine years later, but by then Minkowski was dead, unfortunately. [936] NERNST, Hermann Walther German physical chemist
Wabrzezno, Poland), June 25, 1864
November 18, 1941 Nemst, the son of a judge, was bom only twenty miles from the birthplace of Copernicus [127]. He obtained his doc tor’s degree summa cum laude at the University of Würzburg in 1887 and then, in 1890, became an assistant to Ostwald [840].
[936] NERNST
NERNST [936] He made his first important mark on physical chemistry as a young man of twenty-five when in 1889 he applied the principles of thermodynamics to the electric cell. For the first time since Volta [337] had invented it nearly a cen tury earlier, someone was able to give a reasonable explanation for the electric potential it produced. He evolved a sim ple equation, commonly called the Nernst equation, relating the potential to various properties of the cell. Nernst’s explanation has been replaced by other and better ones but his equation is still useful.
In 1891 he became professor of physi cal chemistry at Gottingen, and got to work on a new textbook of theoretical chemistry, one that made full use of the thermodynamic notions of men like Ost wald. It was published in 1893. In that year he also advanced an ex planation for the ready ionization of compounds in water, a problem that had puzzled the men who objected to Ar rhenius’ [894] theories a decade before. Nernst pointed out that water has a high dielectric constant, that it is an electric insulator, in other words. It is difficult for positively charged ions and nega tively charged ions to attract each other through the insulating water molecules. They no longer hold each other as tightly as they do in the original pure compound and “fall apart” on solution in water. The separated ions could now carry an electric current. In a solvent of lower dielectric constant, the ions would cling together and there would be neither ionization nor the ability to carry an electric current. J. J. Thomson [869] in dependently suggested the same idea, which is therefore called the Nernst- Thomson rule. Nernst became professor of physical chemistry at the University of Berlin in 1905 and a year later announced his most important discovery, usually re ferred to as the third law of thermo dynamics: Entropy change approaches zero at a temperature of absolute zero. From this is deduced the impossibility of attaining absolute zero. One can get as close as patience, expense, and the excel lence of equipment and scientific in genuity permit (and temperatures of only a millionth of a degree above abso lute zero have been attained), but the actual temperature bottom can not be touched. For this Nernst was awarded the 1920 Nobel Prize in chemistry. Nernst’s third law was put into its sim plest form by Planck [887] in 1911. Lewis [1037] went on to show that the law could be strictly true only for sub stances in a crystalline state and this was demonstrated experimentally by Giauque [1178],
Nernst, in 1918, explained how hydro gen and chlorine explode on exposure to light. Light energy, he pointed out, broke the chlorine molecule into two chlorine atoms. The chlorine atom (much more reactive than the molecule) reacted with the hydrogen molecule to form hydrogen chloride and a hydrogen atom. The hy drogen atom reacted with a chlorine molecule to form hydrogen chloride and a hydrogen atom and so on. The reac tion could continue for ten thousand to a million steps on the initial molecular break through light. Light, in this way, sets up a “chain reaction.” Chain reac tions proved useful in explaining many forms of reactions, such as those produc ing polymers (long-chain molecules). Chain reactions of a completely different sort were eventually found by Hahn [1063] and others to produce nuclear ex plosions far more devastating than any ordinary chemical explosion could be. Nernst was also an inventor of sorts but certainly not of the first rank. His most famous invention was a lamp made of ceramic, which could be made to heat to incandescence with a comparatively weak current. However, it had disad vantages and was no competitor at all to Edison’s [788] light, but to Edison’s as tonishment he nevertheless sold the pa tent for a million marks. (Edison firmly believed all professors were impractical dreamers but Nernst certainly was not.) Nernst also invented an electric piano, which was never heard of again. He maintained an inventor’s attitude toward science, too. He announced that in his opinion Roentgen [774] ought to have patented the X ray he had discov
[937] CARVER
CARVER [937] ered and made money out of it (which certainly never occurred to Roentgen). Nernst served his country in World War I and both his sons died in action in that war. Nevertheless, he spent his last years in official disfavor, since two of his daughters had married Jews—which was a considerable crime in the time of Hitler.
[937] CARVER, George Washington American agricultural chemist Born: near Diamond Grove, Mis souri, 1864 Died: Tuskegee, Alabama, Janu ary 5, 1943 The exact date of Carver’s birth is not known, for he was a black, born at a time and in a place where blacks were still enslaved and were chattels rather than men. Vital statistics were not con sidered important in their case. The young infant was technically a slave until the passage of the Thirteenth Amend ment to the Constitution outlawed slav ery in the United States in 1865. When he was only a few months old, he and his mother were stolen by raiders (slave rustlers) and carried off into Ar kansas. The mother was lost forever, but the owner, Moses Carver, was able to get back the baby by trading a three- hundred-dollar racehorse for him. The Carvers adopted him after the law of the land freed him and the child bore his foster father’s last name for the rest of his life. The Carvers tried to get an education for the obviously intelligent youngster, but that was difficult. An elementary ed ucation was eked out, at a black school in another town, and when it came time for college, young Carver had to travel north. He was accepted at Simpson Col lege at Indianola, Iowa, in 1889, and was the first black ever to attend that college. He did well, and after graduation, at tended Iowa State Agricultural College from which he graduated at the head of his class. In 1892 he earned a master’s degree and joined the staff of the school. But a higher duty called. At Tuskegee, Alabama, the Tuskegee Institute, a black college, had been founded by Booker T. Washington, and Carver was invited to join the faculty at a salary of $1500 per year, plus room and board—all the school could afford. In 1896 he accepted the call and returned to the South in order to help blacks obtain the higher education there which he himself had been unable to find. To do this, he re fused more lucrative offers elsewhere. He became director of Tuskegee’s De partment of Agricultural Research, and slowly, with the help of his students, he built up a laboratory out of virtually nothing and rebuilt the played-out land by using muck from nearby swamps and from compost heaps. It was his mission to do the same all over the South. The traditional crops of the region, cotton and tobacco, had robbed the soil of its minerals and the Southern farmer was in a never-ending cycle of debt and fruitless labor. Carver carried on a campaign, in the end suc cessful, to plant peanuts and sweet pota toes in order to enrich the soil. Then, to take care of the surplus of peanuts and sweet potatoes, Carver de voted himself to the development of side products. He became a chemical Bur bank [799], developing not new plant varieties, but new plant products. From peanuts alone, he developed some three hundred types of synthetic material, in cluding everything from dyes and soap to milk and cheese substitutes. From sweet potatoes came 118 by-products. All his work was given freely to the world and he made no attempt to amass any per sonal profit. He continued to regard his work at Tuskegee as of prime importance in bet tering the lot of the black and refused flattering offers to join Edison [788] or Ford [929], where he might have grown considerably wealthier and—since he would then be in the North—live some what more comfortably. He also refused an offer to go to the Soviet Union as consultant to their cotton industry. All in all, the South profited enor mously from the labor of this black bom a slave. In 1939 he was awarded the Roosevelt medal, with a citation reading: “To a scientist humbly seeking the guid Download 17.33 Mb. Do'stlaringiz bilan baham: |
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