In case of any emergency on ship, a box containing CaC2 and Ca3P2 is thrown in sea. The reactions produce C2H2, PH3 and P2H4 which burn with sooty flame. It works as emergency signal for other nearby ships or coasts. The technique is popularly known as

In case of any emergency on ship, a box containing CaC2 and Ca3P2 is thrown in sea. The reactions produce C2H2, PH3 and P2H4 which burn with sooty flame. It works as emergency signal for other near by ships or coasts. The technique is popularly known as Holmes signals.