The Romance of Modern Chemistry

ELEMENTS WITH DOUBLE IDENTITY never free. Phosphorus, however, can be extracted from bone ash by certain processes, and when prepared in this way it is a yellowish-white, waxy solid which can be cut with a knife. It has to be kept under water, for if exposed to the air it combines with the oxygen and is gradually converted into a compound of phosphorus and oxygen. Phosphorus is very easily melted, and if the water under which it is kept is raised to a temperature a little above blood heat, the phosphorus becomes a liquid. It takes fire with the greatest readiness, and if, instead of being melted under water, a piece of phosphorus is heated in the air, it will ignite at a temperature very little above its melting-point. In the dark a lump of phosphorus exhibits a curious glow or phosphorescence, which is directly connected with the action of the oxygen in the air upon it. From what has been said it will be understood that phosphorus is not dissolved by water, but there is one liquid which dissolves large quantities of the element, namely, carbon disulphide. On this property a pretty experiment can be based, for if a little of the solution of phosphorus in carbon disulphide is poured on blotting-paper, the finely- divided phosphorus which is left after the evaporation of the carbon disulphide takes fire spontaneously. Ordinary phosphorus is further extremely poisonous, and many cases have occurred in which children have been poisoned by sucking the ends of matches, in the preparation of which phosphorus is used. Let the reader now draw a mental picture of this yellowish-white, waxy solid, easily melted and readily set on fire, very poisonous and giving a characteristic phosphorescence in the dark, and put side by side with 51 DANMARKS TEKNISKE BIBLIOTEK