Frank Wigglesworth Clarke
Clarke, Frank Wigglesworth
Clarke, Frank Wigglesworth
(b. Boston Massachusetts, 19 March 1847; d. Chevy Chase, Maryland, 23 May 1931),
Clarke was perhaps the most distinguished of the early American geochemists. His compilations of rock, mineral, and natural water analyses provided a basis to explain the chemical processes occurring at the earth’s surface. Many of his concepts concerning the chemical evolution of geological systems are still valid.
He was the son of Henry W. Clarke, a Boston hardware merchant and later a dealer in iron-working machinery, and Abby Fisher Clarke, who died when he was about ten days old.
Clarke received his primary and secondary schooling in the Boston area. In March 1865 he entered the Lawrence Scientific School of Harvard University where he studied chemistry under Wolcott Gibbs. He received the B. S. in 1867. He remained at Harvard for an additional year at which time his first scientific paper, describing some new techniques in mineral analysis, was published. During the subsequent year, 1869, he acted as an assistant to J. M. Crafts at Cornell University. For the next four years he lectured on chemistry in the Boston Dental College and supplemented his meager earnings with newspaper and magazine articles. He reported Tyndall’s Lowell Institute lectures and the proceedings of meetings of the American Association for the Advancement of Science for the Boston Advertiser. He wrote popular scientific reviews, many for periodicals catering to young readers. Foreshadowing the later direction of his career he proposed in 1873, in Popular Science Monthly, a scheme of evolution of the heavy elements from the light. In spite of these varied and time consuming activities, he maintained an involvement in scientific researches. He initiated a series of articles under the general title of “Constants of Nature” for the Smithsonian Institution with the contribution “A Table of Specific Gravities, Boiling Points and Melting Points of Solids and Liquids.”
Clarke accepted an appointment as professor of chemistry and physics at Howard University in Washington, D.C., in 1873. Following his marriage to May P. Olmsted of cambridge, Massachusetts, in 1874, he went to the University of Cincinnati as professor of chemistry and physics, a position he held for nine years. In 1883 he was appointed chief chemist to the U. S. Geological Survey in Washington, D.C., and honorary curator of minerals of the United States National Museum. He retired from these offices on 31 December 1924.
Clarke received honorary degrees from Columbian University in 1891, from Victoria in 1903, from Aberdeen in 1906, and from Cincinnati in 1914. He was honored with the chevalier of the Legion of Honor in 1900.
The forty-one years Clarke spent at the Geological Survey witnessed the development of the United States as one of the foremost centers of geochemical research. As chief chemist he was responsible for the analyses, of thousands of samples of crustal rock, water, and air. Such investigations, were carried out with great accuracy using the best availble techniques. The laboratories gained international distinction and provided a training site for many young aspiring chemists both from the United States and abroad. The associates of Clarke in these enterprises involved the elite of analytical and geological chemistry, including W. F. Hillebrand, F. A. Gooch (designer of the Gooch crucible), Eugene Sullivan (the inventor of Pyrex glass) W. T. Schaller, H. N. Stokes, and T. M. Chatard, and George Steiger. Both major and trace elemental concentrations were sought in the materials under study. Clarke emphasized the importance of all available data stating. “The rarest substances, however, whether elementary or compound, supply data for the solution of chemical problems”.
It is interesting to note that Clarke himself had little proficiency in the laboratory; yet his interest in mineralogy dates to his initial researches. His first published paper in 1868 bore the title “On a New Process in Mineral Analysis.” The studies provided the base upon which Clarke put forth his interpretation of natural phenomena. An annual report of the work done in the Washington laboratory of the chemistry and physics division of the U.S. Geological Survey contained the results from the examination of minerals, rocks, and waters. The vehicles for the transmission to the scientific community of such work and its significance in understanding geological phenomena at the earth’s surface were the volumes The Data of Geochemistry first published as U. S. Geological Survey Bulletin no. 331 (1908; 5th ed., Bulletin on. 770, 1924).
Clarke’s impact upon environmental science derived from his thesis that the chemistry and mineralogy of a rock is a record of past chemical reactions, which in part serves to describe geological events connected with the formation or alteration of the solid phase. The earth’s crust is the site of such reactions and is composed of three domains: the atmosphere, the hydrosphere, and the lithosphere. Since the compositions of the first two zones are relatively homogenous and well-defined, the solid earth was the focus of his studies. The analysis and synthesis of minerals and rocks were the techniques used to define the chemical reactions.
Clarke emphasized the importance of equilibrium considerations in the prediction and descrption of chemical reaction in nature. In the fifth edition of The data Geochemisty (p.10) he states:
The reactions which took place during the formation of the rock were strivings toward chemical equilibrium, and a maximum of stability under the existing conditions was the necessary result…. To determine what changes are possible, how and when they occur, to observe the phenomena which attend them, and to note their final result are the function of the geochemist.
Such advice has been used by subsequent generations of geochemists who have successfully applied equilibrium thermodynamics to the formation and alteration of igneous, sedimentary, and metamorphic rocks.
To provide a baseline for their investigations, Clarke and his associate H. S. Washington sought the average composition of the earth’s crust to a depth of ten miles. They assumed that such an average could be approximated by the average composition of igneous rocks since contributions from metamorphic and sedimentary rocks appeared to be trivial. Their estimate for the composition of the crust was 95% igeous rock, 4% shale, 0.75% sandstone, and 0.25% limestone.
From 8,600 elemental analyses of rocks, Washington selected 5,197 superior assays on the basis of criteria he had devised. The overall average, recalculated to 100% with the elimination of water and minor constituents, turned out to be:
Petrographical analyses upon 700 igneous rocks gave an average mineralogical composition: quartz, 12.0%; feldspars, 59.5%; pyroxene and hornblende, 16.8%; biotite, 3.8%; titanium minerals, 1.5%; apatite, 0.6%; other accessory minerals, 5.8%.
This composition is intermediate to that of a granite and to that of a basalt, the two principal rock types of the earth’s crust. Although many criticisms have been voiced against their computation, usually on the grounds that the sampling of the rocks was neither random nor representative, these results, with only minor modifications, are still valid.
Since silicon is the most important metallic element in crustal materials, it was not unexpected that Clarke’s attention would be directed to the problems of silicates and their compositions and structures. His first paper in this area, “Researches on Lithia Micas “appeared in 1886. Although the laboratory syntheses alteration products, and pseudomorphs of minerals provided Clarke with what he called the natural history of a mineral, he extended his knowledge with the preparation of artificial substances, especially the ammonia analogues of sodium, potassium, and calcium minerals. This new field of investigation provided additional information on the constitution of minerals.
Such work essentially closed the era of silicate mineralogy based upon chemical composition and reactions. The subsequent development of x-ray diffraction and electron microscopy was to provide details on atomic architecture which would give a new foundation to such studies.
Clarke also calculated the average composition of sedimentary rocks, using such data to compute the total amount of sedimentation occurring during geologic time. The argument given is that the total amount of igneous rock eroded is equal to the total amount of sedimentary rock produced plus the dissolved salts of the sea. He calculated that ninety-three million cubic miles of sediments had been produced over geological time.
He extended his interest in inorganic sediments to those precipitated biologically with investigations upon the inorganic constituents of marine invertebrates. He was aware that many important rocks were composed of solids precipitated by the animals and plants of the sea, furnishing, through their shells, silicon dioxide, calcium carbonate and calcium phosphates. He was able to provide some of the first estimates on the relative contributions of such materials to the geological column.
Clarke was closely involved in the formation of the American Chemical Society. Before 1873 chemistry was not accorded much importance in the A. A. A. S. In that year, at a meeting in Portland, Maine, Clarke, with C. E. Munroe, W. McMurtrie and H. W. Wiley proposed the establishment of a subsection of chemistry. This suggestion was accepted and the section first met the following year in Hartford, Connecticut.
In 1876 the New York chemists formed a local society with the name of the American Chemical Society; eight years later the Washington, D.C., chemists created a similar organization. In 1886 Clarke wrote to Munroe, who was serving as chairman of the A.A.A.S. section of chemistry, that it would be most reasonable to form a national chemical society. Three years later a proposal of the New York group was accepted—their name and charter would form the basis of a national society to include both the New York and Washington groups as local sections. Clarke became president of the American Chemical Society in 1901.
Of Clarke’s many works the following are of particular interest: “Evolution and the Spectroscope” in Popular Science Monthly 2, no. 9 (Jan 1873) 320–326; a letter to the editor of popular Science Monthly advocating a sub section of chemistry in the Proceedings of the America Association for the Advancement of Science ibid; 7, no 30. (July 1875), 365; “A preliminary Noticce of the Revision of the Atomic Weights” a paper presented before the chemistry subsection of the American Assocation for the Advancement of Science and review in American Chemical journal1, no 4 (Oct.1879) 295–296 “The Constants of Nature pt. 5—Recalcution of the Atomic Weights” Smithsonioan Nature, pt. 5-Recalculation of the Atomic Weights,” Smithsonian miscellaneous publications no. 441 ; Elements of Chemistry (New York, 1884); “The Minerals of Litch-field, Maine,” in American Journal of Science, 3rd ser., 31 (1886), 262–272; and “The Relative Abundance of the Chemical Elements,” in Bulletin of the U.S. Geological Survey, 78 (1891), 34–42.
See also “Report of the Committee on Determination of Atomic Weights” in Journal of the American Chemical Society 16 (1894), 179–193; “The Constitution of the Silicates,” in Bulletin of the U. S. Geological Survey, 125 (1895), 1–125; “The New Law of Thermochenistry” a paper read before Philosophical Society of Washing ton (see Proceedings 14, 399); “The Data of Geochemistry,” in Bulletin of the U. S. Geological Survey 330 (1908) 716pp. and chemical Abstracts, 2, no, 9 (10May 1908) 1252–1253; “Some Geophycials Statstics;” in Proceedings of the American Philosophical Society 51 (July, 1912) 214–234; “The Evolution and Disintegration of Matter; U. S. Geological Survey paper 132-D(9 April1924); and the Internal Heat of the Earth,” in Scientific American 134(June 1926), 370–371.
With Henry S. Washington he wrote “The Average Composition of Igneous Rocks, “paper no. 462 from the Geophysical Laboratory, Carnegie Institute of Washington, and “The Composition of the Earth’s Crust, “U. S. Geological Survey paper no. 127.
Edward D. Goldberg