On this date in 1790, the very first U.S. patent was granted to Samuel Hopkins on a process for manufacturing potash. Potash can be any material containing potassium. However, potash is most commonly potassium carbonate derived from wood ashes. The term arises from the process of extracting lye from wood ashes in iron pots. Potash can be used in glass making:
Glass made with potash becomes rigid more quickly and becomes harder and more brilliant than soda glass.