The Romance of Modern Chemistry

CHAPTER VI METALS, COMMON AND UNCOMMON NO one can fail to notice that metals and alloys play a very important part in the economy of modern life. It has not always been so in the history of the world, for, “ as every schoolboy knows,” there was a time when tools and weapons were made exclusively of stone. That primitive stage in man’s conquest of nature was followed by the Bronze Age and the Iron Age, and ultimately, when Greece and Rome were at the height of their glory, as many as seven metals were known and utilised. At the present time the number of known metals is very much greater, and innumerable alloys, made by mixing two or more metals, find application in our technical and social life. We see them everywhere, from powerful engines and gigantic bridges down to needles and pins ; we carry them about with us, on our boots, in our pockets, on our fingers, in our hair, and sometimes even in our mouths. The majority of the seventy known elements are metals, and among these there are all sorts and conditions. Only one is a liquid—mercury or quicksilver—and its curious combination of the properties of a metal and those of a liquid render it useful for many special purposes. In the same way, however, as liquid water may be converted into steam by heating and into ice by cooling, so the liquid metal may be boiled, producing mercury vapour, or it may be 61