A leavening agent is an organism or substance that when added to a dough[?] of flour and water causes it to "rise" by evolving carbon dioxide or other gasses that become trapped as bubbles[?] within the dough.
... Keys, scientist
February 1 - S. J. Perelman[?], humorist, author
February 4 - MacKinlay Kantor[?], historian (+ 1977)
February 5 - Walter Gross[?], cabaretist (+ ...