Mildred Cohn was such a star in school that she enrolled in college at age 15, only to have a professor tell her it was “unladylike” for women to go into her chosen field, chemistry.

She did it anyway — going on to become the first woman to earn a Ph.D. in chemistry from Columbia University, in 1937.

Yet she continued to encounter discrimination throughout the 1940s and 1950s when looking for work. Industry positions often specified that only “male, Christian” applicants were welcome. Cohn, who was Jewish, instead worked in lower-ranking academic jobs that were beneath her qualifications.

In 1960, Cohn finally landed a tenure-track position at the University of Pennsylvania’s medical school, where she won renown for deciphering the structures of chemical compounds. But along with the science, she devoted her career to a personal mission: working to make sure others would not face the same obstacles she did.

Her story, and those of eight other female pioneers in the sciences, are featured in Pursuit & Persistence: 300 Years of Women in Science, a new exhibit at the American Philosophical Society in Philadelphia.

The exhibit features dozens of historic documents and artifacts from the society’s collection, most of them never before on public display. Among them is a strongly worded memo from Cohn to her white male colleagues at Penn in the 1970s, advising her peers on how to interact with women and people of color, who were joining the faculty in increasing numbers.

“These new colleagues are sensitive, feeling, perceptive people, not curiosities to be examined, paraded around, ogled, and denigrated,” she warned.

If You Go

What: Pursuit & Persistence: 300 Years of Women in Science
Where: American Philosophical Society, 104 S. 5th St., Philadelphia
Cost: Free. Suggested donation: $2 per person
When: 10 a.m. to 5 p.m., Thursdays through Saturdays, through Dec. 30