ALLEN, EUGENE THOMAS

(b. Athol Massachusetts, 2 April 1864; d. Arlington, Massachusetts, 17 July 1964)

geochemistry.

The son of Frederick Allen, a merchant and manufacturer, and of Harriet Augusta Thomas Allen. Eugene attended Amherst College, from which he graduated in 1887 with the B.A. degree. He then entered Johns Hopkins for graduate study in chemistry, receiving the Ph.D. in 1892. During his graduate years he served as associate in chemistry at Women’s College of Baltimore (now Goucher College), Following a year as acting professor of chemistry at the University of Colorado, he studied at Harvard for two years (1893–1895) and then was professor of chemistry at the Missouri School of Mines (now University of Missouri. Rolla) from IS95 to 1901. At the end of his first year in Missouri he married Harriet Doughty of Arlington, Massachusetts, on 26 August 1896.

In 1901 Allen joined the U.S. Geological Survey in Washington, D.C. On 1 January 1907 he transferred to the Geophysical Laboratory of the Carnegie Institution of Washington when that department was formed from the geophysical laboratory of the U.S. Geological Survey, whose appropriations had been curtailed. There he served primarily as chemist until his retirement on 1 May 1932. On several occasions. during absences of the director, Arthur L. Day, Allen was officially designated acting director of the Geophysical Laboratory. He continued as research associate (1932–1933) following his retirement.

Although Allen had alreadv contributed to geochemistry through a careful analytical study of a sedimentary rock containing native iron in the coal measures of Missouri, it was the influence of William F. Hillebrand while he was at the U.S. Geological Survey that set him on the road to becoming a superior analytical geochemist. The devising of a “clear and logical course to follow” in making a complete analysis, double precipitation as a routine procedure, and the continual search for refinement of technique were lessons he applied well. In turn Allen inspired others to seek the highest precision in their analytical work—at least one assistant, Lmanuel G. Zies, became an important geoehemist in his own right. And a colleague at the U.S. Geological Survey, Arthur L. Day, became his mentor as director of the Geophysical Laboratory and a lifelong collaborator in research, as well as a close friend.

The experimental study of the plagioctase feldspars, the most abundant of the rock-forming minerals, by Day, Allen, and Joseph P. lddings set the format for the principal line of geochemical research at the Geophysical Laboratory. The work was done at the U.S. Geological Survey, funded fov the most part by the Carnegie Institution of Washington through special grants, and published in 1905. In recognition of the role of the Carnegie Institution of Washington in supporting the work, the director of the U.S. Geological Survey authorized its distribution as Carnegie Institution of Washington publication no. 31, which later was designated Publication of the Geophysical Laboratory no. 1.

After the development of equipment for maintaining and measuring relatively constant high temperatures, scientists were able to determine the melting points of the compositional range of plagioclase feldspars with considerable accuracy. (Thenitrogen-gas thermometer developed then remains the fundamental thermodynamic scale for temperature measurement and calibration.) Allen was also responsible for the analyses of high-purity metals used as secondary standards for melting-point determinations. The analyses showed that the plagio-clases consisted of a continuous series of solid solutions that melted in a simple way. the beginning-of-melting curve and the all-liquid curve forming a simple loop (Roozeboom’s type I). The methods he helped develop for measuring the physicochemical behavior of minerals made from exceptionally pure chemicals have served as the foundation for all subsequent phase equilibria studies.

Other works, now recognized as classics, were written in collaboration with John K. Clement, James L. Crenshaw, Clarence N. Fenner, John Johnston, Esper S. Larson, Jr., Herbert E. Merwin, Robert B. Sosman, Walter P. White, Frederic E. Wright, and Emanuel G. Zies, all leaders in their respective fields. They include studies on mineral polymorphism, the processes of ore mineral deposition, the chemical analysis of glass, and the composition of volcanic gases and hot springs.

Allen, White, and Wright placed an upper limit on the stability of wollastonite (CaSiO₃), an important metamorphic mineral, by showing that it inverted to another form at 1190°C. Allen established with Wright and Clement that MgSiO₃, a common mineral in igneous rocks and meteorites, also exhibited polymorphism, in which the transitions produced measurable heat effects. The synthetic compound diopside, a principal end-member of the pyroxenes, which in terms of composition lies between wollastonite and enstatite, was shown by Allen, White. Wright, and Larsen to melt congruently—that is, to a liquid of its own composition (though it was demonstrated by Kushiro and Schairer in 1963 to melt incontinently—to a diopside solid solution and liquid), to exhibit different extents of solid solution toward MgSiO₃ and CaSiO₃, and to have optical and physical properties close to those of natural diopside. In the course of this investigation, a high-temperature heating stage for the petrographic microscope was constructed and another polymorph of MgSiO₃ (now called protoenMnlite) uas discovered. Allen and Clement were the first to show that water is an essential. structurally bound, constituent of the amphibole tremolite.

During the period from 1910 to 1917, Allen was mainly concerned with the determination of sulfur in metallic sulfides and sulfates. He viewed the genesis of ores as primarily a chemical problem and believed the conditions of formation could be obtained by forming the ore minerals in the laboratory. thereby determining the range of conditions of stability in a systematic fashion. Showing great insight into the pitfalls of mineral synthesis, he stated that it is necessary for a chemist working in this field to keep in constant touch with geologists. His sulfide research culminated in the classic study with Zies and Merwin on secondary copper sulfide enrichment (1916). By quantitative study of the reactions of natural sulfides with copper sulfate solutions, they showed that cuprous sulfate reacts more readily than cupric sulfate in replacing the original sulfide. The order of stability of the sulfide enrichment products was determined to be chalcopyrite, covellite, chalcocite. and eventually metallic copper and sulfuric acid. The project was carried out in cooperation with Louis C. Graton and his colleagues at Harvard, and with many copper companies, as part of the Secondary Enrichment Program.

The entry of the United States into World War I resulted in the loss of access to the Jena optical glasses, The Geophysical Laboratory did the basic research for the production of high-quality optical glasses in the United Stales. Determining the composition of the Jena glasses fell to Allen and Zies. The glasses contained combinations of elements that were more difficult to separate and determine accurately than those found in rocks. The two scientists concentrated on the problem of determining boron and arsenic accurately, and in the course of their work devised a series of rapid analytical methods. Another classic study resulted (1918).

For the remainder of his life’s work. Allen took as his text a statement from Thomas C. Chamberlin and Rollin D. Salisbury’s Geology (I. 1904): “It is one of the outstanding problems in geology to determine the origin of the volcanic gases,” Inspiration no doubt was also gained from his colleagues Day and Ernest S. Shepherd, as well as from the enthusiasm of Thomas A. Jaggar, but his experiences in the held with volcanism on the Katmai expedition of 1919 probably determined his interest, Four studies now recognized as classics resulted; (1) on the fumaroles of the Katmai region, Alaska, in the Valley of Ten Thousand Smokes, written with Zies (1923): (2) on the hot springs of Lassen National Park. California, written with Day (1924); (3) on the steam wells at “The Geysers,” California, written with Day (1927); and, perhaps the most famous, (4) on the hot springs of Yellowstone National Park, Wyoming, written with the help of Day (1934). These pioneering studies made available a vast amount of field data and chemical analyses, collected over sufficient time periods to serve as a guide not only to the understanding of geysers, hot springs, and fumaroles, but also lo the production of geothermal energy.

Allen was a kindly, modest man always helpful to his younger colleagues. He was a superb conversationalist and an informative letter writer. His holidays, usually spent in New England, involved hiking and botanical tours of the countryside.

A member of the American Chemical Society. Allen served in 1904 as president of its Washington, D.C., section, the Chemical Society of Washington. In addition, he was a fellow of the Geological Society of America and the American Geophysical Union. The National Academy of Sciences elected him a member in 1930.

BIBLIOGRAPHY

I. Original Works. Allen’s writings include “Native Iron in the Coal Measures of Missouri,” in American Journal of Science, 4 (1897). 99–104; “Some Reactions Involved in Secondary Copper Sulfide Enrichment,” in Economic Geology, 11 (1916), 407–503, written with Kmanucl Zies and Herbert Merwin; “A Contribution to the Methods of Glass Analysis…,” in Journal of the American Ceramic Society, 1 (1918), 739–786; “The Condition of Arsenic in Glass and Its Role in Glassmaking.” ibid., 787–790: “A Chemical Study of the Fumaroles of the Katmai Region,” in National Geographic Society Contributed Technical Papers, 1 (1923), 75–155. written with Emanuel Zies; “The Source of the Heat and the Source of the Water in the Hot Springs of the Lassen National Park,” in Journal of Geology, 32 (1924), 178–190, written with Arthur L. Day; “Steam Wells and Other Thermal Activity at’ The Geysers: California,” Carnegie Institution of Washington Publication 378 (1927), written with Arthur L. Day; and “Hot Springs of the Yellowstone National Park,” in Proceedings of the Fifth Pacific Science Congress, III (Victoria and Vancouver, B. C. Canada, 1934), 2275–2283, written with Arthur L. Day.

II. Secondary Literature. Charles A. Anderson. “Eugene Thomas Allen,” in Biographical Memoirs, National Academy of Sciences. 40 (1969), 1–17, with a bibliography of Allen’s publications:and Margaret D. Foster. “CSW Past-President Celebrates 100th Birthday.” in The Capital Chemist, 14 (1964), 95. There is information on Allen in the personnel files of the Geophysical Laboratory at the Carnegie institution of Washington, covering the period 1907–1964.

H. S. Yoder, JR.