Penicillin; molecular model by Dorothy Hodgkin, ca. 1945.
Penicillin was successful as an antibiotic and treatment for infection well before scientists knew its chemical nature. Chemist and crystallographer Dorothy M Crowfoot Hodgkin (1910-1994) used large punch-card operated tabulators, predecessor to the computer, to help analyse the patterns cast by reflected X-rays. This technique is known as X-ray crystallography.
Hodgkin later won the Nobel Prize for Chemistry in 1964 “for her determinations by X-ray techniques of the structures of important biochemical substances”.