The Girl in the Golden Atom by Ray Cummings, Science Fiction, Adventure, Classics

THE INCREDIBLE SHRINKING GULLIVER!
His name is just the Chemist. He has discovered new worlds -- microscopic worlds. In these Lands Infinitesimal he finds a Love larger than the Universe! Somehow, the Chemist told his friends, the Banker, the Big Business Man, the Very Young Man, the Doctor . . . Somehow he was able to peer into subatomic worlds within his mother's wedding ring through a special microscope. There he found a beautiful woman named Lylda, full of mystery and promise. He must find this woman again! He invents pills to make him smaller and pills to make him larger. But this otherworldly place -- at first a seeming Utopia -- is full of alien strife and civil war. The Chemist does not return! Can his friends use his pills to shrink themselves and find him -- and save him and his love?