In his 1891 novel The Doings of Raffles Haw, Arthur Conan Doyle talks about turning elements into other elements of decreasing atomic number, until a gray matter is reached.
In his 1959 novel Life and Fate, Vasily Grossmans  principal character, the physicist Viktor Shtrum, reflects on Prouts hypothesis about hydrogen being the origin of other elements (and the felicitous fact that Prout's incorrect data led to an essentially correct conclusion), as he worries about his inability to formulate his own thesis.