I Believe It's Magic. Magic. Magic. Circus Man S1 Ep 19

A gunshot in the night announces the arrival of Mr. William O’Hara, a traveling circus proprietor, into the Ingallas’ lives. And this circus has more than talking birds and Congorillas, it has a magic healing powder that can heal/cure anything. Everything except what ails Harriet Olesen which forces Doc Baker and Charles to request William O’Hara to move along. A run in with a wagon leaves Jack in a fragile state and with Laura in tears what’s a Pa suppose to do? Will Jack make it through the night? Is William O’Hara’s magical powder really all that magical?