From the Susan Cheever book, "My name is Bill"
LSD was new and legal at the time Bill took it..
Bill reason for dropping acid may have had more to do with finding a way to quit smoking then helping another alcoholic.
Initially Bill loved acid and recommended everyone take it.
There were grumblings from others within AA but Bills felt since he'd he'd stepped down from his leadership role he was entitled to live life the way a normal person wanted.
Timothy Leary initially approached Bill asking to be included in Bills acid experiments. Leary had already experimented with acid at Harvard University but with disastrous results.
By the end of 1959 Bill had stopped extorting friends to take acid and ended his own experiments.