At this point, acids were defined as substances that split up to yeild Hydrogen ions (H+), but bases yielded Hydroxyl ions (OH-). Brønsted suggested a more general definition in which whenever a proton transfers from one molecule to another, there is an acid-base pair involved; the acid gives up its protons and base accepts it.
A visual chronology of Asimov's ~1500 scientific inventions and discoveries.
