Chemistry, Microscopy, and the Nanoworld

By Cyrus C.M. Mody

In his 1915 textbook Elementary Chemical Microscopy Émile Monnin Chamot noted with dismay that “the American Chemist, usually ready to accept with alacrity all time, labor, and money saving devices, has been strangely backward in taking advantage of the benefits to be gained through the intelligent application of chemical microscopic methods in the industries and in research.”

For a fierce but brief period in the 17th century, chymists (alchemists and those natural philosophers with an interest in matter) had waxed enthusiastic about microscopy. Then, for nearly two centuries, chemists abandoned the microscope as a mere toy. Over time a few interdisciplinary entrepreneurs, such as Chamot, brought microscopy back into chemistry. But today Chamot would be proud: thanks to the instruments of nanotechnology, chemists have once again become ardent devotees of ultramicroscopy.

People have peered through quartz or glass to magnify objects since antiquity but, as with alchemy, the theory of lens making crossed to medieval Europe from the Arab world. By the 14th century Western Europeans had figured out how to grind lenses for spectacles; two centuries later the Dutch had learned to combine multiple lenses, resulting in the telescope and the microscope. When those inventions reached Italy in the 1620s, natural philosophers “swarmed” to the microscope to draw loving portraits of giant, magnified bees, the family symbol of Pope Urban VIII.

Outside bee-mad Italy, microscopes did not catch on until the 1660s. Heightened interest flowed from new ideas about life and matter, ideas that also fed the chemical evolution. One was the “mechanical” philosophy, which held that all matter—even living things—could be analyzed using the mechanical laws of Galileo, Descartes, and Newton. The other was the theory of corpuscles, according to which the world is made up of small particles whose size, shape, and motion determine material properties. Microscopy promised to shed light on the validity and relation of these theories.

Some microscopists thought that corpuscles would soon be made visible. Henry Power, for example, proposed in the preface to his 1664 book Experimental Philosophy: “If the Dioptricks further prevail . . . we might hope, ere long, to see the Magnetical Effluviums of the Loadstone, the Solary Atoms of light, . . . the springy particles of Air, the constant and tumultuary motion of the Atoms of all fluid Bodies, and those infinite, insensible Corpuscles.” The microscope helped forge “chymistry” from alchemy; by applying the systematic methods of the new empiricism to microscopy, natural philosophers hoped that the hidden, invisible (or occult) properties of matter described by alchemists might finally be revealed. Indeed, the most celebrated early microscopical publication, Robert Hooke’s Micrographia, which was published in 1665, is a paean to the new world revealed by the empirical methods of the Royal Society.

Microscopy’s Decline and Rise

By 1700, though, it was becoming clear that microscopes made with hand-ground lenses would not reveal the corpuscular nature of matter any time soon. Chymists despaired of answering fundamental philosophical questions about matter with a microscope and turned to the indirect characterization techniques on which modern chemistry was built. As Hooke put it in his 1692 book Philosophical Experiments and Observations, microscopes “are now reduced almost to a single Votary, which is Mr. [Antoni van] Leeuwenhoek; besides whom, I hear of none that make any other Use of that Instrument, but for Diversion and Pastime” (p. 261). Leeuwenhoek himself used the microscope to observe the physical structure of living things rather than to look for the elusive chemical corpuscles. His intellectual heirs were anatomists, not chemical pioneers like Priestley and Lavoisier. Still, chemists, including Priestley himself, like most scientific amateurs and salonnières, often owned a microscope as an expensive but fashionable toy.

By the 19th century anatomy and chemistry were becoming distinct disciplines, with the microscope as a point of contact. Technological improvements—particularly the achromatic lens in the 1820s—combined with such cultural shifts as the rise of Romanticism gave biological microscopists added authority. These newly confident microscopists had a complicated relationship with chemistry. In part the two communities were rivals for knowledge of the subvisible world. By 1837, for example, Theodor Schwann (founder of the cell theory) and other biologists were using microscopy to argue, persuasively, that yeast was composed of living organisms whose metabolism is responsible for fermenting sugar into alcohol. Eminent chemical authorities—Justus von Liebig, Jöns Jakob Berzelius, and Friedrich Wöhler—attacked Schwann and proclaimed yeast to be a nonliving precipitate. Liebig and Wöhler had only recently synthesized urea, undermining the romantic concept of “vitalism” (that organic chemicals have properties endowed by some mysterious force deriving from living beings). These pioneering organic chemists’ somewhat misplaced opposition to Schwann may have arisen from fears that Schwann’s insistence on living yeast’s role in fermentation marked a return to vitalism.

Still, chemistry, especially through its dyes and stains, offered remarkable tools in making the microscopic world observable. By the 1850s histologists developed a variety of arcane ways to harden, fix, and preserve their specimens using materials like Canada balsam (a resin of the balsam fir). For staining they depended on carmin, a chemical derived from cochineal, a red dye made by grinding females of the cochineal beetle, a parasite of the prickly pear cactus in Mexico. But William Perkin’s synthesis of mauve in 1856 was a watershed. We think of mauve and other aniline dyes for their impact on manufacturing, but they also remade microscopy. By 1862 histologists were using mauve to stain specimens, and the next year they expanded to aniline red, blue, and violet. The new dyes not only differentially stained anatomical structures but were also more standardized (making experiments easier to replicate) and easier to acquire. (For more on Perkin, see pages 8–9, 35 in this issue.)

Henry Clifton Sorby

The microscope began its diffusion from biology into other fields in Victorian Britain. In the early Victorian era, under the sway of Wordsworth and the Romantics, field scientists were thought to have an “authentic,” trustworthy relationship with nature through outdoor pursuits. Natural historians like Charles Lyell and Richard Owen controlled the institutions of British science until the 1850s. The mid-century unrest of Britain’s increasingly urbanized masses, though, led the country’s most influential naturalists to extol taming nature indoors. With proper instruments (the microscope and the aquarium) Britain’s urban masses could be occupied observing nature in their parlors—hence the late 1850s saw a glut of popular microscopy books, such as Edwin Lankester’s Half-Hours with the Microscope.

The Sheffield amateur Henry Clifton Sorby (1826–1908) beautifully exemplified this transition from natural history to microscopy. Sorby was born into Sheffield’s prosperous community of cutlers and toolmakers and was groomed for the family business. His mother (from a Sheffield family but London raised) had a larger vision for his future, however, and fostered Sorby’s scientific aptitude by hiring a tutor in mathematics, anatomy, and chemistry. When his father died, Sorby (aged 21) fashioned himself as an amateur “gentleman of science” by building his own laboratory, where his first experiments measured such trace elements as sulfur and phosphorus in plants—work inspired by the first translations of von Liebig’s works into English in the 1840s.

But Sorby was also an outdoorsman and natural historian. Late in life he even sailed a specially equipped yacht up and down East Anglia doing pioneering work in marine biology. Throughout his life he was an inveterate hiker, and his scientific pursuits naturally turned to geology. What made Sorby remarkable, though, was how he domesticated geology by combining it with microscopy and chemistry. When Sorby heard how lapidaries made thin slices of rock, he instantly realized this would allow light transmission through rock samples, making them amenable to microscopical investigation. By 1855 Sorby was studying microscopic fluid cavities in rock to gain a better understanding of the chemical and physical processes of rock formation.

From terrestrial rocks it was a small step to examining iron meteorites, and from meteorites a smaller step to looking at steel. In some ways, it is surprising Sorby did not study steel sooner. He was dedicated to local scientific organizations, was an officer of Sheffield’s Literary and Philosophical Society from age 22, and eventually became president of the town’s Firth College. It was perhaps inevitable that Sorby should take an interest in the material that made his town famous. Sheffield’s steel firms dominated the international market for cutlery and edge tools—even the coulters of John Deere’s plows—throughout the 19th century. Sheffield’s steelmakers long knew from ocular inspection that the quality of their product depended on its microstructure, the size and texture of its crystalline grains. But Sorby was perhaps the first to systematically prepare steel specimens by etching with acids for examination with a microscope and to relate microscopic observations to steel’s composition, treatment, and quality.

Émile Monnin Chamot

A consummate amateur, Sorby continually opened new fields and then moved on. He left his intellectual heirs working in universities and corporations in newly professionalized disciplines such as geology, metallurgy, and chemistry. His first generation of successors was in Europe—for instance, Ferdinand Zirkel for geology and Heinrich Behrens for metallurgy. Behrens provided the link to chemical microscopy’s most vociferous American proponent, Émile Monnin Chamot. Born in 1868 in Buffalo, New York, Chamot spent almost his entire adulthood at Cornell University. An undergraduate from 1888 to 1891, he wrote a senior thesis on “Some Curious Basic Salts of Lead” under George Caldwell (a student of Wöhler’s); after graduation he stayed to finish a Ph.D. on didymium. In 1897 Chamot finally took a brief sojourn from Cornell when, like many young American scientists of the day, he toured Europe to see cutting-edge scientific techniques firsthand.

Chamot met Behrens at the Polytechnicum in Delft. Behrens, a mineralogist, had adapted his microscopic research to metallurgy, organic chemistry, and biology. According to legend, in parting Chamot asked how he could thank Behrens, to which the older man suggested he teach chemical microscopy at Cornell—sparking a six-decade tradition in Ithaca.When he returned Chamot headed the Cornell chemistry department’s Division of Sanitary Chemistry, Toxicology, and Microchemical Analysis. At this point Chamot considered microscopy an adjunct to his work on safe water supplies. But through this path Chamot became entangled in local politics. By 1901 his findings on Ithaca’s poor water quality led him to charge the city with negligence. This was dangerous territory: another Cornell chemistry professor, A. A. Breneman, lost his job in the 1880s when his unfavorable review of water quality in Ithaca and nearby Geneva raised the ire of local business owners. Likewise, Chamot’s pleas were ignored, and in 1903–1904 typhoid swept Ithaca, leaving over 1,300 sick and more than 80 dead in a town of only 15,000. The cause was traced to residential sewage running into the city’s water supply, exactly as Chamot had warned. Yet, though he had been finally, and tragically, proven right, the soft-spoken Chamot abhorred the dangerous and thankless role of a scientific Cassandra in local politics.

Instead, Chamot rededicated himself to educating and interesting his students and colleagues in “chemical microscopy.” By 1900 he was teaching courses on organic and inorganic microscopical analysis; after 1914 he turned to the microscopy of metals, alloys, and materials of construction. We sometimes forget how much steel manufacturing, which drove innovation in America from railroads to skyscrapers, was the chemical industry of its day. Steelmaking involves mixing iron with chemicals to add or remove trace elements, from standard carbon to exotic silicon and vanadium, and changing temperature and pressure and physically manipulating the metal to rearrange the grains and introduce or eliminate defects to produce desired characteristics. Chamot had his greatest influence in systematically developing microscopy to study this microstructure. Chamot used his microscopy courses to offer future industrial chemists a strikingly visual illustration of how processes like crystallization, sintering, and phase changes proceed.

Many of the lessons of these courses were presented in Chamot’s celebrated 1915 book Elementary Chemical Microscopy and its sequel (co-written with his protégé Clyde Walter Mason) Handbook of Chemical Microscopy (in print as late as 1983). Chamot established a new war-related field by studying the microstructure of firearms, writing The Microscopy of Small Arms Primers in 1922. Appropriately enough, this book echoed Sorby’s work in two ways: in appealing to local industry (here, the manufacturer Ithaca Gun) and in pioneering chemical microscopy for forensics. Sorby, inspired by Bunsen and Kirchhoff, had combined lenses with prisms to invent a spectroscopic microscope that could identify different mineral species in a rock slice. In 1865 Sorby used this method to identify whether minute stains included blood—a technique that actually saw use (though inconclusively) in an 1871 trial.

Postwar: Tom Anderson to Nanotechnology

By the time Chamot retired in 1938, light microscopy had for the first time been joined by a non-optical means of magnification—the electron microscope. Experiments to focus electrons and magnify an object first arose in the early 1930s. Ernst Ruska (who received the 1986 Nobel Prize in Physics) and Max Knoll in Berlin, Günther Rüdenberg at Siemens, and Ernst Brüche at AEG all published in 1931, followed quickly by (among others) Ladislaus “Bill” Marton in Brussels and James Hillier and Albert Prebus at the University of Toronto. By the outbreak of war Marton and Hillier were each separately competing to have their designs commercialized in the United States by RCA. Anxious to have its television technology accepted by the Federal Communications Commission as the standard for commercial broadcasting, RCA promoted electron microscopy. Since electron microscopy and television are closely related, RCA could use dazzling scientific discoveries made with its microscopes to assert the superiority of its televisions.

RCA therefore desperately cultivated customers and uses, particularly in the publicity-friendly areas of biology and medicine. RCA’s director of electronics research, Vladimir Zworykin, hired a young chemist, Thomas Foxen Anderson, to liaise with new users and develop new applications for the microscope. Anderson earned an undergraduate degree in chemistry at Caltech in 1932 and, like Chamot, made a scientific pilgrimage to Europe, where he spent a year developing a new spectrograph. Upon returning he enrolled in the Caltech chemistry department’s Ph.D. program, where he delved into Raman spectroscopy under Don Yost and Linus Pauling. Then followed a long time in the Depression-era job market: from Caltech to a postdoc in surface chemistry, then to the botany department at the University of Wisconsin, and back to teaching chemistry, still at Wisconsin.

When Anderson landed a National Research Council–RCA postdoctoral fellowship in 1940, it seemed like another job in the string. Yet this position would mark a revolutionary turning point for Anderson and for electron microscopy. Working from the RCA labs in Camden, New Jersey, Anderson reported to a distinguished committee of cytologists, virologists, geneticists, and bacteriologists, including Stuart Mudd, Wendell Stanley, and Milislav Demerec. The committee made Anderson’s work a priority and delivered specimens from their labs; Anderson then developed ways to image those specimens and co-published a series of papers with committee members. RCA publicized the work, thereby attracting new researchers to electron microscopy. Soon biologists of all stripes were sending Anderson samples or signing up for electron microscopy time at RCA. Meanwhile, he continued developing new ways to prepare specimens and interpret his own images. As historian of science Nicolas Rasmussen puts it in his 1997 book Picture Control, “through the [RCA] committee’s exercise of power, Anderson’s [specimen preparation] techniques, his aesthetic standards, and his style of interpretation all became models and benchmarks for the work of biological electron microscopists” (p. 54). Anderson, the itinerant chemist, now became the arbiter of a powerful new technique, eventually establishing a renowned program at the University of Pennsylvania.

Still, Anderson’s clients were biologists, not chemists. In the postwar instrumentation revolution that transformed chemistry, microscopy had little impact. Spectrometers, diffractometers, ultracentrifuges, and analyzers all framed the new chemistry, but not microscopy—this despite a remarkable proliferation of ways to image the microworld. Electron microscopy soon segregated into two techniques: transmission electron microscopy (where the beam passes through a thin sample) and scanning electron microscopy (where the beam is rastered over and scattered by a sample). In the 1950s Erwin Mueller at Penn State developed the field emission and field ion microscopes. The field ion microscope could actually image individual atoms arranged in a metal sample; later field ion studies showed diffusion of adsorbates on metal and pictures of single molecules. The 1970s saw the arrival of scanning acoustic microscopy and the first nearfield scanning microscopes.

Ultramicroscopy and chemistry only began to borrow from each other at 17th- century levels after the invention of the scanning tunneling microscope (STM) and its cousin, the atomic force microscope (AFM), in the 1980s. As with electron microscopy, chemists rarely built their own STMs and ATMs, but they developed new and popular uses for them—including those that would breathe life into the idea of nanotechnology. The STM was invented in 1981 by Gerd K. Binnig and Heinrich Rohrer, physicists at the IBM laboratory in Zurich who shared the 1986 Nobel Prize in physics with Ruska. Initially they used the new device to characterize advanced microelectronic components, expanding a previous generation’s use of electron microscopy to understand how new ways of preparing photoresists and etching and cleaning silicon actually affected circuit features. But Binnig and Rohrer soon started using STMs to create basic knowledge about various materials. As physicists from the field of low-temperature electron tunneling, however, they knew little about chemistry and materials science. They therefore formed partnerships with colleagues from surface science and electrochemistry to allow STMs to flow into those communities.

The STM could “see” individual atoms, but the question for all early STM builders was what atoms to look at. In providing the answer, chemists redefined how we think about and represent molecules. The collaboration that produced perhaps the most visually striking results was at IBM Almaden, where a physicist, John Foster, teamed with an organic chemist, Jane Frommer, to produce some of the first STM work to visualize molecules. Foster was using an STM to inspect graphite but saw that his images showed contamination on the surface; he asked Frommer to work with him to understand these contaminants, and she suggested they study organic molecules intentionally deposited on graphite, such as dioctyl phthalate. Eventually they learned to “herd” these molecules with the STM and even to give them a voltage pulse to “dissect” them—that is, to perform a chemical reaction by hand.

This work made Foster and Frommer popular with the early proponents of a new idea called nanotechnology. Its supporters wanted to build materials from the “bottom-up”—using physical probes like the STM and AFM to manipulate chemical reactions and make structures with every atom in a specially selected place. This idea is still far off and may never be achieved. But the ability to use physical devices to manipulate and image chemical processes at the atomic level is here to stay. Microscopy and chemistry cooperate today because, at last, they can do what the early microscopists hoped: see “corpuscles” at work and see how their shape, size, and arrangement do indeed affect bulk material properties. Nanotechnology flourishes at the intersection of new chemical objects—buckyballs, quantum dots, dendrimers—and the instruments that can see and move them.

For Further Reading

Barnett, James A. “A History of Research on Yeasts 1:Work by Chemists and Biologists, 1789–1850.” Yeast (1998), 1439–1451.

Gooday, Graeme. “‘Nature’ in the Laboratory: Domestication and Discipline with the Microscope in Victorian Life Science.” British Journal for the History of Science (1991), 307–341.

Higham, Norman. A Very Scientific Gentleman: The Major Achievements of Henry Clifton Sorby. Oxford: Pergamon Press, 1963.

Mason, Clyde Walter. “The Services of Émile M. Chamot to Chemical Microscopy.” Industrial and Engineering Chemistry Analytical Edition (1939), 341–343.

Rasmussen, Nicolas. Picture Control: The Electron Microscope and the Transformation of Biology in America, 1940–1960. Stanford, CA: Stanford University Press, 1997.

Wilson, Catherine. The Invisible World: Early Modern Philosophy and the Invention of the Microscope. Princeton, NJ: Princeton University Press, 1995.

Cyrus Mody is program manager for emerging technologies in CHF’s Center for Contemporary History and Policy.