The American Chemical Society designated the discovery of baking powder by Eben Horsford a National Historic Chemical Landmark in a ceremony in East Providence, Rhode Island, on June 12, 2006. The plaque commemorating the event reads:
In the mid-19th century, Eben Horsford, Rumford Professor at Harvard University, devised a unique mixture for baking, which he named "yeast powder" and later called baking powder. The acid component, calcium acid phosphate, originally manufactured from bones, replaced cream of tartar, an expensive byproduct of the European wine industry. The mixture of acid with sodium bicarbonate was stabilized by addition of starch and marketed in one package. In the presence of moisture carbon dioxide is released, leavening biscuits, cookies, or other quick baking products. As a result of Horsford's work, baking became easier, quicker, and more reliable.
Written by Judah Ginsberg
Photo Credits: Rumford Collection, East Providence Historical Society.
The author is indebted to the assistance of Edith Arness of the East Providence Historical Society, who prepared the original nomination, provided research materials, and read a draft of this brochure, and to Martin Saltzman of the Department of Chemistry at Providence College, who supplied a valuable addendum to the nomination detailing the chemistry involved in the development of baking powder. Thanks also to Frankie Wood-Black, Janan Hayes, and Paul Jones of the National Historic Chemical Landmarks Program Committee for reading a draft and making invaluable suggestions. Needless to say, any remaining errors are the author's alone.
Designed by MSK Partners, Hunt Valley, Maryland