The ancient Greek philosophers thought that there were only four elements:
earth, air, fire and water. The Chinese alchemists were concerned less with theory and
more with a practical search for the holy grail of the elixir of life, but happened upon
|gunpowder|. Mediaeval alchemists wanted to transmute lead to the perfect
metal - gold. It was not until the time of Sir Robert Boyle (1627-1691) that alchemy was
transformed into the respectable science of chemistry. Boyle recognised elements as
substances that could not be broken down into a simpler form. During his lifetime
|phosphorus| was discovered to bring to twelve the total number of
elements then known, in the late 17th century.