Wow. Not thought of rubber cement in a LONG time.
My Dad was a civil engineer/surveyor and it was used a LOT in the old days for mounting drawings, photographs, etc.
When my Dad was running his own business in the early 1980s he'd buy the stuff by the gallon can. Grandpa was also an engineer/surveyor... same thing. When I cleaned out their office at the house after my Dad died there were a bunch of old brush bottles of rubber cement, most of them the really old tins, with varying levels of dried rubber cement in them.
My guess is that with the advent of computers, rubber cement is virtually unknown in those professions anymore.
One of the things that the guys who worked for my Dad used to do was to collect the "spill over" dried cement and roll it into ever larger rubber balls. Not only were they fun to bounce but they also served as a very handy tool for picking up, or erasing, excess rubber cement from drawings.