The Romance of Modern Chemistry

NATURES BUILDING MATERIAL about the part played by the elements and about the relations in which they stand to the infinite variety ol naturally occurring substances. Amongst the elements themselves there is great diversity. Some are gaseous substances, like oxygen, hydrogen, nitrogen, chlorine, and helium ; two are liquids under ordinary conditions, namely, mercury and bromine; while the great majority, chiefly metals, are solid substances. But this division of the elements into gaseous, liquid, and solid substances is some- what arbitrary, and is valid only for the particular con- ditions which prevail on our earth. On those heavenly bodies which are much hotter than our planet, many of the elements with which we are familiar as solids exist in the gaseous condition. In the extraordinary heat which prevails on the sun even iron is a vapour. It must be borne in mind that the elements are found in nature mostly in some form of mutual combination. Only a few of them occur in the uncombined state, or “ native11 as it is called. The noble metals and some other elements, such as copper, sulphur, oxygen, and nitrogen, belong to the latter class, but the minerals composing the great bulk of the earth’s crust are com- binations of the other elements with oxygen and sulphur. The fact that some elements never occur in the native condition becomes intelligible when we make ourselves acquainted with the properties of these elements. Take the case of phosphorus. The chemist has been able, by certain subtle processes, to extract this element from the ashes of bones, but it has such an aversion to the state of single blessedness, that unless precautions are taken to keep it out of contact with air, it reverts to the combined state and unites with the oxygen of the atmosphere. It is therefore easily understood why phosphorus is never 31