“letter from Rabbi Avraham Rice.”
There is a great biography of Rabbi Rice that quotes many .similar writings by him and others who were committed to Torah.
I. Harold Sharfman
The First Rabbi: Origins of Conflict Between Orthodox and Reform : Jewish Polemic Warfare in Pre-Civil War America : A Biographical History
Pangloss Press, 1988
I think it is out of print but I found used copies on several internet sites.