The Romance of Modern Chemistry

CHEMISTRY AND ELECTRICITY chemical discoverer and manufacturer. It has a re- markable power of splitting up compounds into simpler parts, provided it is applied to these compounds while they are either in the dissolved or the molten con- dition. The value of the electric current for this purpose was demonstrated by the famous English chemist, Sir Humphry Davy, who succeeded in showing that potash and soda, which up to the time of his experiments had been regarded as elements, were really compounds. It was by passing an electric current through fused caustic potash that Davy first obtained potassium, a metal which is so ready to interact with air and moisture that it can be preserved only under naphtha. Potassium has the consistency of hard butter, and it may easily be cut with a knife; the clean, fresh surface of the metal obtained by cutting is quite shiny, but it rapidly tarnishes, owing to the action of air and moisture. When a small piece of potassium is thrown into water, hydrogen gas and caustic potash are immediately gener- ated, and the heat of the reaction is so intense that the hydrogen catches fire. The pouring on of water, therefore, a process which is usually associated with the extinction of fire, may in some cases actually lead to the production of flame. Sodium, the metal which Sir Humphry Davy first isolated from caustic soda by the action of the electric current, is very similar to potassium, but rather less active. The decomposing action of the electric current is known as “ electrolysis,* and soon after Davy’s time another famous English investigator, Michael Faraday, discovered the laws which govern this phenomenon. He showed that when two wires connected with the poles of a battery were immersed in the solution of a salt or in 297