W I L ~ E ~ OSTWALD, who made a special study of the characteristic features of eminent scientists, distin- guished between two types of research personalities: the classicists and the romanticists. The former work independently and place more stress on the content than the form of presentation; also they usually are not in- clined to teaching, particularly not large groups of stu- dents. In contrast, the romantic type works more ex- pansively and tries to awaken the interest of many in his achievements. Moreover, he is usually talented in speaking and writing; he attracts students readily and tends to develop them into collaborators. The mem- bers of both categories, however, regard research as an end in itself. They are not primarily interested in practical applications of their findings or in the mone- tary rewards that may result. However, there is a third class of research men: the inventors. They have the gift of recognizing the desires and needs of the great mass of people before the latter themselves know what they want and require, and by fulfilling these desires they become benefactors of mankind. Carl Freiherr von Welsbach was a h e example of this type of gifted discoverer.

The Auer family hailed from Wels in Upper Austria. Carl Auer's father, Alois Auer (1813-69) was uncom- monly gifted. He began as apprentice printer and on his own initiative studied English, French, Italian, and pedagogy. He brilliantly passed an examination a t the University of Vienna and then became a language teacher in Wels and Linz. His memoir on the estab- lishment of a great 'Lpolygraphic" government institute brought to him directly the post of director of the Court and State Printing Office in Vienna (1841). Under his direction, this establishment acquired an international reputation. The Vienna press had the richest collection of types in the world. At the 1851 London Industrial Exhibition the Vienna establishment was awarded all five of the highest honors.

Carl Auer, the youngest of four children, was born in Vienna in the old buildings of the Court and State Printing Office on September 1, 1858. His mother (born 1831) came from a business family in Wels. The boy was educated at a Gymnasium and then a t a Real- schule in Vienna where he passed the final examination in 1887. He lost his father a t 11, and the mother had to see to the education and bringing up of the children. Throughout his life Auer was closely attached to his mother, who was taken from him in 1910.

STUDIED UNDER LIEBEN AND BUNSEN

Even as a young boy, Auer was attracted to chem- istry, and he made it his chief subject as soon as he

FRITZ LIEBEN University of Vienna, Vienna, Austria (Translated b y Ralph E. Oesper, University of Cincinnati)

entered the University of Vienna. His professor was Adolf Liebeu (1836-1914). Robert Wilhelm Bunseo (1811-99), with whom Lieben had studied and taken his doctorate in 1855-56 at Heidelberg, was recognized as one of the leading European chemists and teachers. Auer went to Heidelberg in 1880 and stayed four semesters, receiving the doctorate in 1882. As a student he showed the tenacious diligence, which so often characterizes those who have a special aptitude for science, and he studiously avoided the distractions of student life. Bunsen seemingly was impressed by the reserved Austrian student and recognized that the young man was endowed with exceptional experimental skill and observational powers. Bunsen's instruction became the foundation on which Auer built his life's work. He always held the great teacher and investiga- tor in high and grateful regard. After Bunsen's death he acquired his library.

RESEARCH ON RARE EARTHS

I t is said that Auer's interest in the problem of the rare earths was awakened in Heidelberg-an area which he was destined to advancemightily, even though many eminent chemists had previously been active in this field.

Full of zeal and new ideas, Auer returned to Vienna and re-entered Lieben's laboratory. First of all he took time out to fulfill his military obligations. His first scientific study (1883) was presented before the Vienna Academy of Sciences. I t dealt with "the earths of gadolinite from Ytterby." I t described an improve- ment of the separation procedure by means of the basic nitrates introduced by Bunsen. He precipitated 10% of the earths as oxalates, ignited them to oxides, which he then added to the solution of the nitrates, thus pro- ducing basic nitrates. In this way the ytterbia and erhia earths, for example, were separated into groups which could then be further divided by fractional re- crystallization.

As is well known, Bunsen, along with Kirchhoff, had made spectrum analysis a scientific tool. Here also Auer a t this time made notable improvements in the apparatus for producing spark spectra. I t was thus made possible to follow much more closely the separa- tion of the rare earth metals. In 1885 Auer was able to announce his first really great achievement, namely, the separation of didymium, the twin of lanthanum, into two new elements which he named neodymium and praseodymium. There had been numerous previous indications that didymium actually represented a mix- ture of elements, but Auer was the first to carry out an impeccable separation. He introduced the fractional

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etc.). This manufacture now progressed despite vicious attacks and troublesome legal conflicts. Auer's mantles were the first that were really usable. The earlier at- tempts of other inventors had yielded products that did not give enough light or were too fragile or too expen- sive. There is not space to relate how the Auer burner enabled the gas-lighting industry to survive for a com- paratively long time in competition with the growing use of electricity. The prolonged patent litigation like- wise cannot he discussed here.

INCANDESCENT OXIDE RLAMENTS FOR ELECTRIC LIGHTS

Auer's other researches adhered to his motto: "Plus lucis" (more light), which appears on the Auer crest. First of all he tried to adapt the great light emissivity of the thorium oxide-cerium oxide mixture to electric lighting. The mixture was applied to platinum wires and when the current was passed a brilliant light re- sulted. The wire melted and the metal oxides continued to glow in wonderful fashion. Unfortunately, when the current was switched off the light went out and could not he revived by a further application of the c ~ r r e n t . ~ Auer then tried a metal with a higher melting point than platinum, namely osmium. Because of its brittle- ness, he was forced again to invent a special process, which was the earliest usable method for preparing metal filament lamps. In one process osmium tetroxide was precipitated hot on platinum or the platinum wire was passed through a slurry containing osmium; the platinum was then vaporized by intense heating. In the second process osmium was deposited hot on carbon threads or fibers, or the osmium was made into a paste with collodion or a sugar solution, the mass then extrud- ed, and the collodian denitrified and burned away. This is only a partial account of what Auer described in his patents. The osmium incandescent bulb was subse- quently further developed especially by the Auer Gesell- chaft, a German company. The advantage of the os- mium incandescent bulb as contrasted with the carbon hulb is shown by the fact that the latter requires 3.5 watts per candle power as opposed to 1.5 watts for the osmium hulb. Admittedly, Aner missed using tungsten and tantalum for metal filament lighting bulbs, hut his method of shaping difficultly fusible metals remained the preferred process.

Around 1900 the Austrian authorities requested Auer to take over the direction of the iron works a t Treibach in Carinthia. He set up there a large chemical research laboratory from which he then developed the Treihach chemical works. First of all, the earlier findings regard- ing praseodymium and neodymium were confirmed and their respective atomic weights were determined (140.57 and 144.54; the modern values are 140.92 and 144.27). Also a part of the operational procedure for mannfactur- ing osmium bulbs was developed in the Treihach lah- oratory in collaboration with Anton Lederer.

THE AUER LIGHTER

From among the many researches conducted during this period, only one will be mentioned, namely, the utilization of the considerable quantities of cerium sul- fate accumulated from the working-up of the monazite ' Inspired by Auer's mantle, Walter Nernst also used mixtures

of rare earths in his electrical inoandescent lamp.

232

sand. Twenty years earlier, in Bunsen's laboratory, Auer had seen the sparking of cerium metal when scratched or drawn over a rough surface. Since the pure metal was too costly to utilize this characteristic for ig- nition purposes, a mixture of the cerite earths was sub- jected to fusion electrolysis with an iron cathode. It was found that the sparking ability of the resulting cerium-iron is dependent on the iron content of the alloy. The optimum is at 30y0 iron. Many other alloys of cerium with various metals were prepared but none was as good as this "cerium steel" for igniting gases and vapors of volatile liquids. The Auer lighter became almost as famous as the incandescent mantle. The pro- duction of cerium-iron reached approximately 100,000 kilograms annually by 1930; it served to prepare 500 million flints which could be used for 500 billion ig- nitions, and replaced six billion boxes of matches.

IDENTIFICATION OF OTHER RARE EARTHS

From this time on, all of Auer's researches were carried on in his laboratory a t Schloss Welsbach, after he had turned over the direction of the Treibach chemi- cal works to Dr. Fattinger. Auer now turned his atten- tion again to the yttrium earths. After isolating the erhium-ytterbium group, the latter was further sep- arated by fractional crystallization of the ammonium double oxalates in excess ammonium oxalate solution. Erbium (discovered by Mosander in 1843) and thulium (discovered by Soret and by Cleve in 1878-79) were thus separated out, and in the course of the operations an al- teration was observed in the relative intensity of the spark spectrum of the ytterbium. By further fraction- ation Auer, in 1905, came to the undoubted conclusion that ytterbium must consist of two elements. A pre- liminary announcement (1905) and a paper in the Lieben Festschrift (1906) on the employment of the spark spectrum for testing the homogeneity of elements were followed by a detailed account (1907) in which the two newly discovered elements with atomic weights 172.90 (now 173.04) and 174.23 (now 174.99) nrere given the names "aldebaranium" and cassiopeium."

Georges Urbain had made the same separation, though somewhat later than Auer, but the French chemist published earlier. He suggested the names "ueo-ytterbium" and "lutetium," which were accepted by the International Atomic Weight Commission. However, the German atomic weight commission assured Auer's priority; the main constituent of Marignac's "ytterbium" (about 90%) was continued to be called ytterbium, and the second constituent, follow- ing Auer's suggestion, was given the name cassiopeium (though the name lutetium continued in use by some). The study of the spectra of his thulium fractious oc- cupied Auer until his death, His last paper (1926) dealt with the element 61 (the present promethium) which he could not find in monazite sand.

Auer's l i e work, a chain of discoveries and inventions, included others of interest. For example, in his factory a t Vienna he had the first ten tons of the residues from the preparation of uranium salts from Joachimsthal in Bohemia worked up and the first considerable amounts of radium salts were prepared in this establishment. He also prepared the precious polonium, ionium, and actinium salts that are still in the possession of the Vienna Academy of Sciences. His researches on

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spectroscopy and his improvements of spectrum apparatus had a permanent effect. The standard studies of the Austrian scientists Exner and Haschek and of Eder and Valentas were inspired by Auer's studies and greatly aided by his gifts of rare specimens of the highest purity. Among the permanent applica- tions of the rare earths is their use in the coloring of glasses. For instance, praseodymium tints glass green- yellow, neodymium tints glass red-blue.

Auer married when he was quite mature and already a t the height of his career. Three sons and a daughter resulted from this happy marriage. Numerous honors came to him from the state and scientific societies, in- cluding, of course, election to the Imperial Academy of Sciences in Vienna. He was made a baron in 1911; the title was hereditary. Accordingly, he is often re- ferred to as Auer von Welsbach.

He was a man of the laboratory rather than of the pen. For the most part his papers are short. He gave few references to the literature since he was usually working in little explored territory. He preferred tele- grams to letters, and a t every festive occasion in the life of this writer's father (Adolf Lieben) Auer's telegram was invariably the first to arrive expressing his con- matulations and his gratitude to his former teacher.

~EXNER, F., AND E. HASCAEK, "Die Spektren der Elemente bei normalen Druck," 2nd ed., 1911; EDER, J. M., AND E. VALENTA, ''Atlw typischer Spektren," 1911.

He ordinarily worked alone; only on special occasions did he employ the help of a few well-tested associates. He had no talent for teaching. He loved the beauties of nature and was an ardent hunter and fisherman. Increasing deafness in his later years forced him to give up hunting; he then took up motoring.

On August 2,1929, he suffered excruciating abdominal pains and knew that death was near. He made a final visit to his laboratory to bid farewell quietly and he- roically to his beloved instruments and specimens, and then returned to bed. The end came on August 4, 1929. A useful life had come to its end, a life filled with' merited brilliant successes, the fruits of hard work.

ACKNOWLEDGMEXT The writer is indebted to Professor Bruhl of the

University of Vienna for information regarding the Auer family and for the photograph.

BIBLIOGRAPHY D'ANS, J . , "Carl Auer Freiherr von Welsbaeh," Ber., 64A, 59-97

i l Q R l > \ - - - ., . SEDLACEK, F., "BIBtter fiir Geschichte der Technik," 1934, Heft 2.

This contains much material on the history of incandescent bodies and carbon and metal filament bulbs.

MAYER, F. E., "Pioniere der Technik," 1945, pp. 45-52. WEEKS, MARY E., "The Discovery of the Elements," Chemical

Educ. Publ. Co., Easton, Pa., 1957. K ~ E ~ R U N T ~ C ~ E I N E R , E., ''Oe~terrei~hische Naturforsoher und

Teehniker" (pnblished by the Austrian Academy of Sciences) 1951, pp. 122-24.

VOLUME 35. NO. 5, MAY, 1958