How glass drove scientific progress

We think of scientific progress as the domain of individual scientists — but glass was arguably just as important

Published April 24, 2020 6:00PM (EDT)

Laboratory glassware (Getty Images)
Laboratory glassware (Getty Images)

Adapted from "The Alchemy of Us: How Humans and Matter Transformed One Another," by Ainissa Ramirez. Published by The MIT Press. All rights reserved.

In the late 1800s, thermometers were one of the few tools that scientists had to probe a chemical reaction. At the time, chemistry was limited to knowing how hot things got (the temperature), how much they weighed (the mass), how much space they took up (the volume), and how much they pushed the container walls (the pressure). Many scientists noticed that their thermometer readings were higher than they should be. It turned out that thermometers did not return to the proper baseline once they were cooled. The heating and cooling and heating and cooling and heating and cooling that the thermometers underwent modified the glass so that the bulb, which held the mercury, changed its shape, causing the mercury to creep up. This meant that subsequent temperature readings were not to be trusted. A young German chemist called Otto Schott had the solution. Originally from a glass-making family in Witten, Schott moved to the city of Jena in 1882 to run a small-scale operation, in partnership with a physicist and a microscope maker. By tailoring the amount of boron, Schott was able to build a glass that did not adjust its physique when heated, allowing thermometers to make proper readings.

Otto Schott cranked out different flavors of glasses throughout the 19th century. One was glass that did not alter its form with heat, allowing thermometers to display proper readings. Another was optically superior and perfect for scientific telescopes and microscopes. A final one did not dissolve in water, acid, or other liquids, making it suitable for laboratory experiments. At the heart of his new creations was boron, though boron played different roles in each of Schott's new glasses. Schott's glasses had versions with small, medium, and large amounts of boron, the way a chef can make a sauce with different levels of spice—mild, medium, or hot—based on the amount of pepper in it. For glasses with improved optical properties, a small bit of boron was added to windowpane glass, giving the glass a better ability to bend light. For glasses that did not expand when heated, Schott added lots of boron. Boron tightly grips other atoms with stiff bonds, like a strong spring, causing the resulting glass to resist expanding when it got hot, unlike other glasses. Finally, for glasses to be able to withstand dangerous chemicals like acids, the amount of boron was decreased to a medium level. Boron likes to bond with other atoms, but its bonds are weak in acids. So some of the boron was taken out of harm's way and substituted with other compounds. Together, all these ingredients stabilized the glass in these harsh environments.

Soon, the glasses designed by Schott became the most desired scientific glass on the planet, and Germany became the main source of all glasses for microscopes, telescopes, and laboratory ware (beakers, flasks, and test tubes). Every scientist wanted optical instruments with the name JENA inscribed on them. For other glassmakers, penetrating this glass market seemed impossible. One company in upstate New York realized that its only chance was to use science.

Corning Glass Works was a family-run company that moved from Brooklyn, New York, to Corning in 1868 with the promise of the canal to transport products and coal from Pennsylvania to keep its furnaces hot. Corning mostly made decorative glass and tableware, and soon also hand-blown glass for Edison's light bulbs. If they were going to compete with Jena glass, though, they knew they needed more science to create new offerings. Corning started to move away from using glass recipes passed down from one generation to the next and began to apply the scientific method. One of the first things Corning's management did was tell their workers to write down what they added to a glass melt, so that a batch could be repeated if need be. Corning also began an unusual practice for a glass factory at the time: they hired scientists.

Starting in 1908, chemists were on Corning's payroll and the investment was working out to be a wise one. To differentiate themselves from other glass companies and to compete with German products, Corning needed technical personnel. Scientists at Corning knew that boron was a key ingredient in these new glasses, and eventually, by trial and error, they created a version of a borosilicate glass called Nonex (short for NON-Expanding glass). Unfortunately, Corning could not penetrate the labware market with it. Its early glass was no rival to Jena glass, which had a nearly fifteen-year head-start. Additionally, German glass enjoyed low tariffs, since it was an educational product. Customers saw no reason to buy an American-made glass, when the price of the superior glasses from Germany was not prohibitive. Corning's management had to find a domestic market for their borosilicate glass and reached out to the most lucrative business in the nation to help keep the company afloat: Corning tapped into the big industry of the railroad.

In the early 1900s, the tentacles of railroads reached some of the farthest corners of the country. In addition to annihilating space, the railroad also compressed time with its speed. That speed came at a cost, however. As trains became faster, many more catastrophic accidents and collisions occurred and with that came a need for better signaling to increase safety. Signals on the tracks told trains not to proceed, with warnings from hot arc lights with red glass covers. On rainy or snowy days, however, accidents occurred more frequently. In addition to the inclement weather, another cause for the increase in accidents was the frailty of glass.

Glasses on train signals were between a rock and a hard place on days with bad weather. The interior of the glass signal was heated by the hot arc light, causing it to expand; the outside, however, was dramatically cooled by the rain or snow, causing it to shrink. The conflicting messages within the glass gave rise to pent up stress; when prolonged this stress resulted in broken glass. A red glass alerts the train to stop, but a broken glass is no longer red and tells the conductor to proceed, giving a false—and possibly deadly—message that it is safe to pass, potentially causing a colossal collision. And as if the weather was not enough for the glass to contend with, mischievous boys used train signals for BB gun target practice, smashing the red glass into pieces with a single pellet. The railroad needed better glass to mitigate the weather and the delinquents and Corning's strong Nonex glass did the trick.

Corning's glass rarely failed. Corning soon became a victim of its own success, however. When the railroad adopted Corning's glass, there was a boom in sales, but the indestructibility of the glass meant that once the railroads purchased their hardy glass, they didn't need replacements. The meteoric increase in sales was followed by a precipitous drop. This lack of built-in obsolescence, or a limitation that would have required additional sales, caused the company to scramble for new glass Help would come, of all places, from a cake.

One summer afternoon in 1913, Jesse Talbot Littleton, a physicist and one of Corning Glass Works's newest scientists, came in to work with a sponge cake baked by his wife, Bessie. J. T., as Jesse preferred to be called, and Bessie were southerners; he was from Alabama and she was from Mississippi. They had moved to Corning from Ann Arbor, Michigan, where J. T. was a physics professor a year prior and, together, they were trying to get accustomed to their new Yankee home in Corning, New York. In a spirit of southern hospitality, J. T. Littleton brought in a cake. The cake was not just a social offering, though; it was a science experiment. For the last two weeks, J. T. had been trying to convince his colleagues of the benefits of cooking with a glass container, but his colleagues laughed at the notion. For generations, people had been told to keep glass away from heat. So baking with glass seemed ridiculous. Little did they know that Littleton was not only a southern boy, but also a glass man.

Littleton was obsessed with glass. He talked about glass at the dinner table. When Jell-O came for dessert, he'd break it apart slowly and show his children how it broke like glass. He even had hopes of being buried in a glass coffin. What made him so certain about his claims about the ability of glass to be a cooking container was that he did his 1911 dissertation at the University of Wisconsin on the heating properties of glass. For the rest of the scientists, who were chemists, the heating of glass was unknown. These scientists assumed that the thick walls of the glass would prevent food from cooking evenly and that the heat would not spread as well as it would with a thin metal pan. J. T. Littleton, a physicist, knew otherwise.

When his colleagues did not listen to his words, his southern sensibilities didn't take kindly to being mocked. So he decided to follow them up with action. He got some help from Bessie. Bessie Littleton liked company. She was raised on a remote Mississippi plantation where visitors were few. At her new home in Upstate New York she asked J. T. to bring people from work over for dinner. At barely five feet tall, with her dark hair in a bouffant style, she was slight, talkative, and dogmatic. With Bessie things had to be just so and she had very strict rules that J. T. had to follow: no lying or liquor; no cigarettes or cigars; and no cussin' or colored people at her table. The long and lanky J. T., with his tall frame, eyeglasses, serious eyes, permanent pout, and understated grace, complied by bringing over a fellow scientist, H. Phelps Gage. All evening, Bessie chided Gage, who was a bachelor, to get married. While the men talked about glass after dinner, Bessie had a captive audience for something that had been troubling her.

A few days earlier, Bessie's new Guernsey casserole dish, which she only used one other time, broke. All night the men talked about the indestructibility of glass and she insisted that these smart alecks ought to make cookware that did not break. The next day J. T. got two cylindrical Nonex battery jars, about as wide as a basketball, cut off the bottom to make round dishes, and brought them home to Bessie. Bessie didn't cook. She had servants to do that. As a child in the south, her servants were freed black slaves who could not escape the grip of the plantation. As an adult in the north, she hired white immigrant girls, whose families came to New York State for work. While Bessie was no master chef, she dominated with her baking. As soon as J. T. gave her an indestructible glass dish, she immediately got to her favorite kitchen task and turned sugar, eggs, flour, butter, milk, vanilla, and baking powder into a white cake. Using every bowl and utensil in the kitchen, she poured the batter into her newfangled dish and baked. What emerged from the oven was an evenly brown cake with a color surpassing that provided by her metal dishes.

The next day, J. T. Littleton brought the cake into work and everyone, not knowing about the baking experiment, reported that the cake was good. Littleton then told them that this cake was baked in glass, causing scientists to scratch their heads and men in management to rub their chins. These scientists found that the cake actually baked well with an inviting color of brown on top. Littleton relayed to his colleagues how easy it was to remove the cake from the smooth glass pan, unlike metal cake pans. His science colleagues did not think glass, if it survived, could make a cake as delectable as the one Jesse brought in, and, in a sense, they ate their words.

They asked that Bessie try out other foods and report how the glass pan worked. So Bessie, as the resident domestic scientist, had a few items cooked, from French fries to steak to cocoa, although she had a penchant for southern dishes of grits, cornbread, and collard greens. The pan performed well, the food didn't stick, and the glass pan didn't retain the flavor of the food the way a metal skillet did. On hearing about the success of this glass for cooking food, the Corning management saw promise. But they had to make a few changes and learn a few more things. First, the formulation of Nonex had to be altered, since it contained lead. The scientists made a borosilicate glass without lead for this bakeware. Next, they had to test the strength of the glass, dropping a weight as heavy as a can of soup onto different types of dishes to see how they survived the rigors of a kitchen. While earthenware cracked with a weight dropped at six inches and crockery broke at ten inches, borosilicate glass laughed off the impact, untouched, even when the weight was dropped waist high. After these impact tests, the team had to figure out how the glass cooked food. Bessie reported that food cooked quicker than in a metal pan, which was the opposite of what they believed would happen. They got to the bottom of this with an experiment.

A scientist dipped a Nonex pan into a liquid chemical bath full of microscopic bits of silver. The silver settled on the surface, coating the outside with a thin layer, giving it a mirror finish. Then, they baked two cakes: one in a simple Nonex pan and one in the mirrored one. After baking, they noticed that the cake with the silver coating did not cook well. What they learned is that the heat from the oven walls, like the rays of the sun, transmitted through the clear glass, cooking the cake, while the mirrored surface reflected that heat back. This showed them that the glass pan cooked differently than a metal pan. A cake in a metal pan gets heated from the hot air in the oven and the heat from the oven rack. The glass, meanwhile, was letting heat into the cake a third way, from the invisible rays of heat, like the sun, which browns our skins and the crust of a loaf of bread.

To commercialize this glass with a new purpose, it needed a name that informed the consumers, mostly women, what this new glass did. The first commercial piece on the market was a pie tin, which was initially called "Py-right." It was renamed Pyrex in 1915, to relate to the earlier product, Nonex, and to sound more futuristic and medical, like Latex or Cutex. Sales of Pyrex were initially flat, but after the company listened and responded to customers' needs, for example reducing the weight of the ovenware, Pyrex soon became a standard item in households. By 1919, over 4.5 million pieces of ovenware were sold. To encourage more sales, Corning created many shapes and sizes and colors, learning their lesson from the railroad glass episode, which made Pyrex a standard Christmas gift. Corning still had its eye on glass for labware, however. An opportunity to enter that market would be a gift of war.

In 1915, with America's potential entry into the war, it became clear to the American government that it needed the ability to make glass for military applications. Jena glass was regarded as the best in the world, but imports from Germany were dwindling. American companies, such as Corning Glass Works, were encouraged years before to create a German glass substitute. Legend has it that President Woodrow Wilson asked Corning's management to develop an alternative to the German products in preparation. These glasses would be used by American soldiers in gun sights and binoculars, by sailors in sextants and periscopes, by airmen for aerial cameras and rangefinders, by army doctors for thermometers and vials of medicines, and in the laboratory by chemists for the synthesis of explosives.

At the precipice of America's entry into the war, Corning had a borosilicate glass, although the ideal Jena formulas were still locked up in German patents. Corning and many other companies wished they could get hold of these recipes. They would get their wish. What the American companies may not have known is that laws of peacetime do not hold during war. When the United States entered the war, it confiscated thousands of German patents (nearly 20,000) as part of its war booty. Impenetrable German monopolies protected by patents, for dyes like mauve and drugs like aspirin, were blasted open with one of America's secret weapons. This weapon was based not on combustion, but on the legislation of the Trading with the Enemy Act. With it, German science, the science of the enemy, became fair game to Americans and American companies. Buried within those patents were those recipes for specialty glasses.

After the war, Corning introduced a range of new Pyrex products, filling in for the shrinking supplies from Germany. In laboratories now there were Pyrex petri dishes, test tubes, and flasks. In homes, there were Pyrex cooking dishes, oven door windows, and percolator tops. In automobiles, there were Pyrex headlights, battery jars, and pressure gage covers. America had unknowingly entered the Glass Age, whereby Corning created a new American industry of scientific and specialty glass. To keep this comfy cushion of no competition for their consumer commodities, Corning pushed for legislation, a tool they grew to understand, to prevent the influx of German glass into American markets after the war. Huge tariffs were placed on German glass, preventing Germany from monopolizing these markets as they had done in the past. These actions were out of view for most Americans and most scientists, who used Pyrex glasses to find the causes for diseases in glass petri dishes, and developed drugs to fight them in glass test tubes.

What citizens and scientists did not know was that glass also provided containers that cooked up a new narrative of American innovation and its scientific prowess. There was no doubt that America was a science superpower, but what was unknown at the time was that the United States now had the upper hand, particularly in glass, made possible by a curious combination of war and cake. No scientific lab was complete without glass. Through the use of glass, we gained an understanding of how our bodies work, how the heavens move, and how other worlds exist in a drop of water. Glass helped to change our perspective.

Ironically, glass helped to order our lives, but its transparency is brought into being by the chaos within it. The atoms in glass are not given enough time to line up like soldiers, so they sit frozen in place in disarray, as in a snapshot of kindergartners during recess. Glass is full of disorder, but the clarity of glass helped us make sense of the world with the lenses and beakers and flasks it created. Since antiquity, glass was treasured for its beauty, but glass also allowed for the cooking up of new drugs, formulas, and medicines.

By Ainissa Ramirez

Ainissa G. Ramirez, Ph.D. is a science evangelist who is passionate about getting the general public excited about science. Technology Review named her as one of the world’s 100 Top Young Innovators for her contributions to transforming technology.  She has been profiled in The New York Times, Fortune Magazine, CBS News, Inside Edition, Fox News, CNN, NPR, ESPN, Time Magazine as well as scientific magazines (Scientific American and Discover Magazine). Her newest book, "The Alchemy of Us," published in April 2020, examines eight inventions—clocks, steel rails, copper communication cables, photographic film, light bulbs, hard disks, scientific labware, and silicon chips—and reveals how they shaped the human experience. 

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