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  • Writer's pictureDale DeBakcsy

The Ice Woman: Mary Engle Pennington’s Revolutionary World of Refrigeration.

In the early 20th century, buying and consuming food of any sort in an urban center was a fraught proposition, particularly in the days before the Pure Food and Drug Act of 1906 which brought some measure of oversight to the rank charlatanism that ran amok in the late 19th century. Feces-contaminated meat, diseased milk, spoiled dairy products, and adulterations of every possible manner were rampant, and while the reason for this was often just unfettered capitalism doing what it does in the search of profit before all other considerations, a good amount of it was also ascribable to simple ignorance about the best practices for the collection, storing, shipping, and displaying of food goods. 

The result was sickness, death, and food waste on an unparalleled scale. While usually putting a stop to problems of such a large-scale is the result of many people working over the course of decades to bring gradual change, in the case of the promulgation of sweeping new best standards for food, and the creation of the technology and practices to allow them to succeed, we have more or less one sole individual to thank: Mary Engle Pennington (1872-1952). By temperament, she was a warm and soft-spoken Pennsylvania Quaker, but by accomplishment she was a veritable dynamo, as effective among government circles as in private industry, a business owner, one of the nation’s most prominent and respected public scientists, and an unfailing font of knowledge for the country’s grandest efforts to solve hunger problems the world over.

She was born on October 8, 1872 in Tennessee, but early in life she and her family moved to Pennsylvania to be closer to her mother’s Quaker relations there. A devoted reader from a young age, who came by her love of the natural world through the hours spent gardening with her father, she was entranced by chemistry at the age of twelve upon checking out a book of medical chemistry in the local library. Enthralled by it, she found that the terminology was beyond her, and took it upon herself to go to the University of Pennsylvania and ask if there was anybody there who might explain the harder parts to her. 

We all want this to be the part of the story where an understanding and patient old professor happens to overhear her query, and, taken aback by someone so young expressing such a self-determined interest in chemistry, establishes a weekly informal meeting with her where, point by point over tea, she is led through the mysteries and wonders of the chemical world. Unfortunately, the result was slightly more prosaic than that, with the university saying that they couldn’t help her at the moment, and that she should come back later, when she was older. 


She apparently took the advice to heart, however, and in 1890 commenced classes at University of Pennsylvania’s Towne Scientific School. In a harbinger of her future interests, her coursework centered largely around chemistry, hygiene, and biology, and within two years she had completed the coursework to earn a Bachelor’s degree. Unfortunately, like many US universities of the time, the University of Pennsylvania did not award science degrees to women, and so she had to make do with a Certificate of Proficiency in biology. Her work, however, had impressed Edgar Fahs Smith (1854-1928), who had worked as a professor at the University of Pennsylvania (with two brief breaks) since 1876, and would continue to do so until 1920, a forty-four year career of service that saw him regularly accept and advocate for women as scientific researchers when the rest of the scientific community could barely be persuaded to accept them as students. 

Smith was a distinguished researcher in the fields of electrochemistry and the study of the more exotic metals, who was also respected for his attempts to teach students the history of chemistry in addition to its purely technical aspects. Under Smith, Pennington authored her dissertation, “Derivatives of Columbium and Tantalum” which show the imprint of Smith’s interest in more obscure metals (columbium is known today as niobium, and resides in the fifth group with the other metal Pennington studied, tantalum, the two transition metals often making guest appearances in each other’s most common minerals). Paradoxically, she was awarded a PhD for this work in 1895 from the institution which would not reward her a Bachelor’s three years earlier, and in fact she went the rest of her life possessing a doctorate but no Bachelor’s degree.

The years that followed showed the breadth and adaptability of Pennington’s mind, as she studied physiological and botanical chemistry at the University of Pennsylvania and Yale before taking up a post as director of the Woman’s Medical College of Pennsylvania’s Clinical Laboratory (long readers of the Archive will recognize the WMCP as the Quaker-founded institution that stood as one of the first places in the United States to offer women medical training, which featured Mary Putnam Jacobi, Ann Preston, Anandibai Joshee, and Rebecca Cole among its alumni. Fun fact: this was also the institution from which the fictional character Dr. Quinn, Medicine Woman, graduated!). 

Here began her tendency to juggle two to three large-scale projects simultaneously, which would have been disastrous for a person of lesser drive and competence, but which she carried out easily and successfully for the next four decades of her professional career. In 1902 she and Elizabeth Atkinson founded the Philadelphia Clinical Laboratory, a private company that did chemical and bacteriological analysis for hospitals, and then in 1904 she added a position as bacteriologist at the Philadelphia Bureau of Health to her list of official duties. 

It was here at the Bureau that she carried out her first studies in food science, tasked with determining what the source of the city’s generally sub-standard dairy supply was. This investigation bore all of the hallmarks of her later work - an open, non-confrontational approach to industry that showed them methods to better identify and deal with problems - a focus on potential difficulties at each stage in the food chain, from production to transportation to storage - and the development of new standards and procedures that found themselves exported throughout the nation, becoming before long common practice. 

Her success in Philadelphia brought her to the national stage, and in 1905 she was offered a position at the US Department of Agriculture’s Bureau of Chemistry, which she maintained for two years alongside her duties at the Philadelphia Bureau of Health, presumably exploiting some wormhole in the space-time continuum known only to her. Her work was of such high caliber that after just three years the chief of the Bureau of Chemistry, Harvey Wiley, nominated her as the head of a newly established department, the Food Research Laboratory, which would be the basis for some of her most far-reaching innovations in the chemistry and technology of food preservation for the next decade. She developed methods for measuring the rate of bacterial growth in meats and dairy goods, and used them to determine optimal temperatures for the transportation and storing of each food product, and to then design new railroad cars and storage facilities to subdue bacteria in transit. Her determination of 29-31 degrees Fahrenheit as the best temperature for shipping eggs was fought by the industry, which did not want to invest in new refrigeration cars, but soon became the standard (today, the FDA recommends a 40-45 degree temperature, in case you were curious). 

After World War I, former US Food Administration director Herbert Hoover was given the mammoth task of feeding the war-ravaged and starving nations of Europe, and he tasked Pennington as the nation’s chief expert on food transportation with the job of coordinating the food industry, shipping industry, storage industry, and government in getting as much food as safely as possible to Europe with the least amount of spoilage, a service for which she was awarded the Notable Service Medal in 1919, and which was responsible for the saving of countless millions of lives from starvation. Not resting on her laurels, after the war she deepened her studies of the impact of refrigeration on foods, joining American Balsa Company as its director of research and development in the creation of new refrigerated railroad cars, creating a perishable food consulting business in 1922 which she ran until her death in 1952, and directing the Household Refrigeration Bureau of the National Association of Ice Industries from 1923 to 1931. 

The 1920s and 1930s saw dramatic change in the technology of domestic refrigeration, and Pennington saw the potential of the new devices to radically improve the health of the nation’s families, and reduce their domestic expenses. While in the 19th century keeping food cool was the job of the noble ice box - a literal wooden box into which a weekly shipment of ice would be packed - by the 1920s ammonia-based cooling technology brought over from Germany was driving the first residential refrigerators marketed by Frigidaire, which were in turn revolutionized by General Motors’ idea of using freon as a replacement refrigerant, which served as the global refrigerating chemical of choice until its role in ozone depletion was uncovered, and the Montreal Protocol of 1987 called for its replacement with other chemicals, such as HFCs and HFOs. Pennington kept herself at the forefront of these developments, writing articles lauding the superiority of refrigerators to old ice box technology, and developing best use practices and specifications for the new appliances. 

With the arrival of World War II, Pennington, though sixty nine years of age, was summoned once again to her country’s aid, as a consultant to the War Shipping Administration’s R & D Branch in its task of feeding not only an army overseas, but the global civilians left destitute in war’s wake. She never truly retired, continuing her work as a consultant and author up to the end of her eighth decade on this planet, enjoying the company of her persian cat, and regularly receiving new awards and accolades from the numerous industries whose practices she had impacted for the better, and from a nation whose children grew up free from the regular food-born pathogens that had cut such a swath through previous generations thanks to her lifetime of service. Pennington passed away of a heart attack on December 27, 1952.


Along with the biographical portraits you can find of her in the Shearers’ Notable Women in the Physical Sciences and Grinstein’s Women in Chemistry and Physics, there was a sizable writeup of her in the September 6, 1941 issue of The New Yorker which is available on their online archive, while Google Scholar has a number of her papers from the 1910s through 1930s available without paywalls, so if you’re interested in the fascinating world of how food was collected, stored, and shipped a century ago, check it out!


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