Hydrogen

The fifteenth entry is l’ammoniaca come vettore, and the first noun carries an Egyptian god into a hydrogen terminal. The ancient world knew a salt gathered near the shrine of Amun, in the desert west of Egypt, and Latin called it sal ammoniacus, the salt of Ammon. Ammoniacus is an adjective and says nothing more than belonging to that god and that place. Italian kept the adjective in plain view. L’ammoniaca is the feminine of ammoniaco, and il sale ammoniaco still stands in the dictionaries beside it, so the word is shaped like a description of a thing rather than like a name for it. English went the other way. It cut the adjective back and fitted it with the ending used for newly isolated substances — « magnesia », « silica », « ammonia » — so that the word now looks like a coinage of the laboratory and carries no temple in it at all. The same god survives in one more English word that no chemist ever connects to this one: the coiled fossil « ammonite », named after the ram horns of Amun.