Ivy Poisoning, Buttermilk and Copperas for

"Wash in copperas and buttermilk three or four times a day. Have seen this used and it helped." The copperas and buttermilk is very good when applied to the parts immediately after the poison is discovered. The copperas acts very much like sugar of lead and in some cases is very much more effective.

Source: Mother's Remedies: Over One Thousand Tried and Tested Remidies from Mothers of the United States and Canada, T. J. Ritter