Epsom Salt is Magnesium Sulfate, an inorganic salt containing magnesium, sulfur and oxygen. It was named after the spring in Surrey, England where the naturally-occurring mineral was discovered in the water. Despite the name, Epsom salt is not what you put in your fries. It is called salt because of its chemical structure. Long known as a natural remedy for a number of illnesses, Epsom salt has numerous health benefits as well as many beauty, household, and gardening-related uses.