The story of Cranesbill, how potash got its name, and why we use the same mineral to clean lakes and make donuts.

Geranium maculatum, May 21st — *Geranium x cantabrigiense ‘Biokovo’* *, May 21st*

Among the many treasures out in the old barn are an assortment of chemical products from the now dissolved Rush & Hebble Co. of Indianapolis. Here is the wondrously diverse Alum. Nearly all formulations of alum are double salts bound to hydrated sulfate. Being that a salt, scientifically speaking, is any positively charged ion bound to any negatively charged one, alum’s composition can contain just about any cation: sodium, ammonium, chrome, etc. The most common commercial form is potassium aluminum sulfate and is known colloquially as potash alum or, sometimes, tawas.

Alum was used in ancient Mesopotamia to fix red dye to textiles. Evidence suggests this process dates to before 2000 BC when the early Iraqis traded for it with Egypt. The Romans used alum to preserve leather, the same reason my father in law kept some around in his barn. Today, alum is used in a stunning array of applications. It can be found in a styptic pencil to stop bleeding, for example, or as an adjuvant to vaccines. It is used in modeling clay and for extracting the phosphorous out of creeks and lakes in order to control algae. It is a startling realization that the additive we use to help doughnuts achieve a palette pleasing crispiness is the same we add to toothpaste as a whitener and to textiles as a flame retardant.

Potash is one of those words that sounds like it should belong to a different era, like quill or scurvy. The name indeed comes from a pre-industrial method of boiling wood ashes in a pot and scraping out whatever was left, usually some potassium carbonate. It was a lot of work for a little potash. These days it is harvested from massive natural deposits formed millions of years ago by the evaporation of ancient seas in Canada, Russia and Belarus. The origin of the name tawas remains slightly less certain. The large potash deposits throughout Canada, including near tribes of the Odawa (or Ottawa) indigenous Americans, may account for the derivation, but this is largely conjecture. Tawas City, Michigan derives it’s name not from the mineral, but rather Chief O-ta-was from the Saginaw band of Chippewas who were known to camp along the shores of Tawas Bay and has, so far as is known, no connection to potash. The most convincing explanation is that tawas is the Tagalog word (a language used in the Philippines) for a rock-like compound used to treat body odor. It is no coincidence that this magical stench absorbent mineral is the multitalented Alum.

A block of potash, potassium aluminum sulfate — *Chunk o’ tawas*

Alum is a known astringent, which explains its use in the styptic pencil, and is found harbored in the roots of at least two well known garden perennials historically harvested for this use. One is the aforementioned Heuchera, discussed here. The other is wild Cranesbill.

Geranium maculatum, or Cranesbill, is a herbaceous perennial woodland rhizome native to eastern North America. It naturally prefers shade, but mine grow happily in fairly direct sun, and will tolerate a range of moisture conditions. It produces small, upright, usually unbranched stems with pale pink to purple five petalled blooms in late spring. The leaves are deeply cut and palmate with 6 to 12 inch petioles stretching cloud-ward from the base. They tend to form large clumps of long-lived clones that have spread from individual plants. The fruit precipitates as five cells with one seed each and a long beak like column resembling a crane’s bill, hence its common name. Other aliases include old maid's nightcap, alum bloom, and alumroot (a term also used for Coral Bells). Nearly every part of the wild cranesbill contains alum, but the root is especially dense and has been employed for millennia to treat any manner of ailments. Like other alum bearing vegetation, the plant is antiseptic, diuretic, tonic, and highly astringent (vasoconstrictive), and was used by the Mesquakie Indians in tea for toothache and painful nerves and mashed into paste for treating hemorrhoids.