Epsom salt
Epsom salts was the common name for the chemical compound known as magnesium sulfate (MgSO4 • 7H2O), that was used as a home bath salt. 

After being roughed up and detained on Gosis' species homeworld, Malcolm Reed inquired to Jonathan Archer if the guard would bring them some Epsom salts, to soothe his blisters, if he asked politely. Archer told him that he would not count on it. ()

See also 
 Neptune Bath Salts

External link 
 

de: Epsom-Salz
Chemical compounds