April 5, 1939
Dear Dr. Apgar:
Yesterday at a conference with Dr. Squier and Dr. Watson it was agreed that, until further decision, it was wise not to use cyclopropane or ethylene in the anesthesia on the operating room floors.
It was felt that, although the incidence of explosion may not be greater, even though we felt that to be a debatable point, if we should have an explosion at the present time with such a recent one appearing in the public press we would be held responsible by both the public and the management of the hospital for using a form of anesthesia that carries with it an unusual risk. It was felt advisable to have this understood by all the anesthetists so that if operators ask for these  anesthesias, they should be told that the heads of the three surgical services had decided on discontinuing it for the time being.
Sincerely yours,
Allen O. Whipple, M.D.