Hartshorn

[2] Hartshorn was used to treat insect bites,[3] sunstroke,[4] stye,[5] and snakebites.

It was more popular in the 1700s and prior as a forerunner of the modern baking powder[7] but is still used today in traditional German, Swiss, Polish, Dutch and Nordic recipes such as A half-teaspoon of hartshorn salt can substitute for one teaspoon of baking powder, and this is commonly done in Americanized recipes.

However hartshorn salt is different from baking powder in that the goods baked with hartshorn salt are crispier, retain intricate designs better, and can be kept out in the open air for longer without becoming stale or hard.

When heated, the ammonia and carbon dioxide gases are released, and the smell eventually dissipates.

Ammonia released during the baking process reacts with glucose and fructose to form intermediate molecules that in turn, react with asparagine (an amino acid found in nuts, seeds, and whole grains) to form acrylamide, a carcinogen.