In the historical heyday of salt making on Cape Cod, not only table salt was produced. On the Local Food Report, Elspeth Hay describes how a byproduct was used for making washing soda for detergents, tanning leather, and dying cloth. What's more, the cold brine leftover could be used to make Epsom salt, or magnesium sulfate.
Find out more on Elspeth's blog, Diary of a Locavore.
Cape Cod's Long History of Making Salt, Part One