I've heard many times of the first systematic study of static electricity: Otto von Guericke would spin a ball made of sulfur and rub it by hand, building up an electric charge. To make a sulfur ball, he would pour molten sulfur into a hollow glass globe, wait for the sulfur to harden, then break the glass container. Ironically, he could have done away with the sulfur and just used the glass ball instead! In fact years later that's just what other scientists did. So the question is, why sulfur? Where did he get it in his head that sulfur had these properties? It seems a weird thing to me to use. He must have heard someone else mention that sulfur gave off electric sparks if you rubbed it enough or something, right? Anyone know the story?