Magnesium sulfate
Faraday is best known for his work regarding electricity and magnetism. His first recorded experiment was the construction of a [[voltaic pile]] with seven [[Halfpenny (British pre-decimal coin)|British halfpenny]] coins, stacked together with seven disks of sheet zinc, and six pieces of paper moistened with salt water. With this pile he decomposed [[Magnesium sulfate|sulfate of magnesia]] (first letter to Abbott, 12 July 1812).