Bring a luxury mineral spa experience to your home bath with a Westlab Epsom Salt Bath Bomb. In the early 17th Century, people would flock from all over the UK to drink the so called 'medicinal, healing waters' of the Epsom Spa. Epsom Salt, also known as Magnesium Sulfate, has since become a bathroom staple, used to naturally relax and revive tired, aching muscles.