🔥 1790
Making Pot ash and Pearl ash by a new Apparatus and Process
U.S. Patent X1 · 1790
From the abstract
An improvement, not known or used before, in the making of Pot ash and Pearl ash by a new Apparatus and Process; that is to say, in the making of Pearl ash, 1st by burning the raw Ashes in a Furnace, 2nd by dissolving and boiling them when so burnt in Water, 3rd by drawing off and settling the Ley, and 4th by boiling the Ley into Salts which then are the true Pearl ash...
Note
The very first U.S. patent. Signed July 31, 1790 by President George Washington, Secretary of State Thomas Jefferson, and Attorney General Edmund Randolph — all three signatures personally on the document. Pot ash (potassium carbonate, leached from wood ashes) was a colonial cash crop used in soap, glass, and gunpowder. Hopkins's improvement was an extra burning step that more than doubled yield. The patent ran one paragraph. The original was lost in the 1836 Patent Office fire and reconstructed from the inventor's records — given the 'X' prefix that marks all such restorations.