The now-forgotten transmutation controversy hung on apparent evidence of mercury transforming into gold
When in 1900 Ernest Rutherford and Frederick Soddy, working at McGill University in Montreal, figured that thorium was spontaneously turning into argon by radioactive decay, Soddy exclaimed ‘This is transmutation!’ To which Rutherford thundered back, ‘For Mike’s sake Soddy, don’t call it transmutation. They’ll have our heads off as alchemists.’