Who was A P Barton?
I don't know, but his 1892 booklet on The Bible and Eternal Punishment is, still after 120 years, one of the best arguments for Unity's theology of a benevolent God.
According to James Dillet Freeman in The Household of Faith, "Charles and Josephine Barton, who published the magazine The Life in Kansas City and had a Truth movement of their own" were also students of Emma Curtis Hopkins.