Hi Hamilton,
I think your ancestor Salmon is the younger brother of my ancestor William Chapin. There is a letter from William's older sister Salome's daughter Emeline Dean to her Uncle William talking about her Aunt Mary Ann who lived in Iowa but had been held up in Ohio due to her ill sister Ellen. This jives with the Salmon B. Chapin who lived in Ohio and eventually moved To Iowa. Also, my ancestor William had a son he named Salmon in 1858, probably in honor of his younger brother who had died in Iowa in 1856.
I cannot yet find any evidence regarding William's parents.
Wonder if you have any ideas? Thanks.