The connexion between matter and electricity, to which the authors have already made reference, appears very clearly for the first time in the phenomenon known as electrolysis. One should enumerate the facts briefly, and afterwards state the conclusions which have been drawn from them. M. Faraday was the first person to investigate these phenomena carefully; his experiments were made during the years 1833–1835. He introduced the notation which is usually adopted. The substance decomposed by the current is the electrolyte, the decomposition take place by electrolysis, and the two metals which convey the current to the solution are the electrodes. The electrode which is connected to the positive pole of the battery is the anode, the other is the cathode. The substance which appears at the anode is the anion, the other is the cation. Faraday also discovered that the decomposition of substances could be obtained without the use of an aqueous solution.