Popularised by
Anton Mesmer in the late 18th century,
animal magnetism was later replaced by the modern day
synonym Hypnotism. It was literally believed at the time to be a form of
magnetism different from
ferro-magnetism, and attracted serious research in its day. It failed to meet the rigorous standards set by
science but remained
fashionable and
popular nonetheless - it could be said to be one of the first
homeopathic treatments.
From an aesthetic viewpoint, animal magnetism is a more poetic and charming term than hypnotism, and doesn't deserve its current death in the English language.