Horsford's research was interrupted by the American Civil War, but in 1869 Horsford finally created an already-mixed leavening agent by using cornstarch as a buffer. Rumford Chemical Works then began the manufacture of what can be considered a true baking powder. Throughout his career, Horsford continued to experiment extensively with possible techniques and preparations for baking powder. Horsford's leavening products were marketed originally as "Horsford's Yeast Powder" and later as "Rumford Baking Powder". They were packaged in glass bottles and later in metal cans. In 2006 the Rumford Chemical Works in East Providence, Rhode Island were designated a National Historic Chemical Landmark in recognition of baking powder's impact in making baking easier, quicker, and more reliable.