The Romance of Modern Chemistry

ELEMENTS WITH DOUBLE IDENTITY only in outward appearance, but in the value we set on them and in the uses to which they are put. The diamond is very highly prized as a gem, and fetches in the market far more than its weight in gold. All real diamonds which the reader has ever seen have been obtained from natural sources; and diamond mining is a regular form of enterprise. Many attempts have been made in recent times to manufacture diamonds, reminding one of the efforts of alchemists to convert lead into gold. Reflection, how- ever, shows that these modern attempts are considerably less ambitious. Their aim is, not to change one element into another, but to convert one form of a given element into another form. The forms of carbon other than the diamond are easily obtainable, and the endeavour to change some of this plentiful material into a more valu- able article is very natural. More than that, the attempt to manufacture diamonds has been actually successful from the scientific and laboratory point of view, although not from a commercial standpoint. Moissan, the French chemist, working on the idea that diamonds are carbon which has been crystallised under great pressure, dissolved amorphous carbon in a crucible containing molten iron, heated the crucible in the electric furnace, and cooled it suddenly by plunging into molten lead. The temperature of molten lead is very much lower than that of molten iron, so that the outside portions of the latter in the crucible solidified immediately. As the iron inside this crust gradually solidified, enormous pressure was produced ; for iron, like water, expands when it passes from the liquid to the solid state. The carbon, therefore, which was dissolved in the iron crystallised out under great pressure. 54