Voltaic pile
Before the voltaic pile was invented, people could make only static electricity. With the voltaic pile, they could make electricity that keeps flowing for some time. Along with this, it was an invention that could be easily made. With this kind of electricity, scientists could do a lot of "new" things. For instance, when new kinds of metal were discovered, the electricity from a voltaic pile could "sort" chemicals. This way, small but very pure bits of these "new" metals could be made.