Potash Kiln

Introduction

Text-to-speech Audio

An important part of Newlin Grist Mill's approach to history is that the staff and volunteers at the site learn about historical processes by actually doing them and documenting the experiences. This comes from the field of "experimental archaeology." One of the projects that has been done onsite is the making of potash.

Images

The potash kiln at NGM.

Image of clay kiln surrounding a large iron pot, with an arched fireplace at the base.

Lye is leached out of wood ashes with water and empties into the iron kettle.

Lye is carried from the wooden ash barrel via a wooden trough and into the potash kettle.

The grey crust that forms on the sides of the kettle as the lye water is boiled is potash.

Close-up image of the heated potash kettle.

Backstory and Context

Text-to-speech Audio

Potash is a chemical substance that was used in making fertilizer, glass, soap, gunpowder and dyeing fabrics. In the 18th century, the primary source of potash was the ash from native hardwood trees. The basic chemical compound potassium carbonate was extracted by leaching the ashes in big iron pots to dissolve out the soluble components. Evaporation of the solution through percolation resulted in the production of potash.

An article published in the Pennsylvania Gazette in 1750 noted that potash was "a Commodity that no Nation hardly can be well without." So important was potash in early America, the very first US patent was issued in 1790 to Philadelphian Samuel Hopkins for improving the process and equipment for making it.

Sources

Patent No. 1, Explore PA History. Accessed December 17th 2020. https://explorepahistory.com/displayimage.php?imgId=1-2-988.

Mitchell, John. "An Account of the Preparation and Uses of the various Kinds of Potash." Pennsylvania Gazette (Philadelphia) December 18th 1750. , 1-1.

Image Sources(Click to expand)

Newlin Grist Mill