Yaffe's papers reflect his interest in the history of McGill and of chemistry, as well as his involvement in the construction of the Otto Maass Chemistry Building. Historical materials include photographs of F.M.G. Johnson, cartoons of McGill personalities as well as eight original Johnson cartoons; approximately 60 photographs of a chemical laboratory near Trenton, Ontario (ca 1910); snapshots of the Chemistry Department Ph.D. Open House (1967); portraits of McGill chemistry professors; clippings and biographical notices of McGill and chemistry interest; and an autograph document by Otto Maass agreeing to a division of profits from a discovery with W.H. Hatcher. Files on the Otto Maass building largely comprise photographs (approximately 115) of the building under construction and of the opening ceremonies as well as speeches, press notices, and related correspondence.