Reference

William Gilbert, also known as Gilbert, conducted experiments to determine which materials could be charged, which he referred to as 'electric' or 'elektriks'. According to the search results, Gilbert tested various materials and notably used amber in his studies of static electricity. He observed that certain minerals, unlike metals, could exhibit electrical properties. Gilbert's work with amber led him to coin the term "electric force" since amber is called "elektron" in Greek. The materials he tested to determine if they were 'elektrics' included amber and possibly other minerals that demonstrated electrical properties. This pioneering work laid the foundation for our understanding of electricity and magnetism.