Mary Letitia Caldwell  Mary Letitia Caldwell (December 18, 1890 – July 1, 1972) was an American chemist. Growing up she valued education and strived to achieve. She was an instructor at Western College teaching chemistry. She was known for being unique and descriptive along with being family orientated. Maria was in a wheel chair due to muscular disability. Most of her work centered on amylase, a starch enzyme, most notably finding a method for purifying crystalline porcine pancreatic amylase. She spent sixty years doing this. Caldwell was born in Bogota, Colombia, to American missionaries. She earned her bachelor's degree from the Western College for Women in 1913 and taught at the school until 1918. She earned her M.A. and Ph.D. from Columbia University in 1919 and 1921. She suffered from a progressive muscular disorder which made her wheelchair bound for life. She came from a family of five siblings, all of which valued higher education. She received her BSN in 1913 from an all women's college Western College for Women in Oxford, Ohio. She then became an instructor for that school until 1918 when she went to further her studies at Columbia University. In 1919 she received her M.S. and her PhD in 1921 from Columbia University. She then became the first women instructor in the chemistry department at Columbia University. In 1951 she retired from teaching and began her studies in enzymes, specifically amylase. After graduating from graduate school at Columbia University, Caldwell became the first Chemistry professor at Columbia University from 1948 to 1949. She became the only female member of the senior faculty in the chemistry department, becoming the first woman to attain the rank of assistant professor at Columbia. She attained the rank of full professor in 1948. Caldwell had a progressive muscular disability, and was confined to a wheelchair by 1960. Despite this, her 9th floor office at her research facility, Chandler Hall, never changed. In 1960 she received the Garvan Medal from the American Chemical Society, an honor awarded annually to a US female chemist. During her time as a chemist, Caldwell did research on a type of enzyme called amylase. She spent a lot of her time trying to purify enzymes because she was not satisfied with the commercial material. She attempted to find a more pure form of amylase and she was able to develop a method for isolating crystalline pancreatic enzymes. After receiving her M.S. and Ph.D. at Columbia University in 1919 and 1921, respectively, Caldwell was hired as an instructor in 1922.