Try these links to Mt. Zion Primitive Baptist Church web site for a wealth of old writings:
Articles and books in html files
Articles and books in pdf files
Includes writings of old Baptists and others, such as: Backus, Booth, Brine, Hercules Collins, D'anvers, Fawcett, Gano, Gill, Keach, Kiffin, McLean, J. B. Moody, Abel Morgan, Orchard, Philpot, Rippon, Ryland, Spilsbury, Samuel Stennett.