Nitrate film is extremely flammable and is considered hazardous: http://youtu.be/7mZDt8vYMBw?t=1m.
If the film is gooey, bubbly, powdery, or has a slightly sweet odor (not vinegary) and is 35mm, it is most likely degrading nitrate, and if it is exposed to hotter temperatures can even self-combust. Almost all nitrate motion picture film is limited to 35mm stock produced before 1951. Always consult with the AV Archivist if you think you may have nitrate film. Tips for identifying nitrate film.
Always store film flat. If the film came wrapped in plastic, remove the plastic. Label can with a Sharpie on the can’s top and side. Any accompanying documents should be foldered. If replacing the can, photocopy original label and tape to to the top of the new can.
Consult AV Archivist. Wind to a core, place in archival can, and house in cold storage or explosion-proof nitrate cabinet.
Note: Healthy nitrate film is prized for its tonal depth. If the film is in good condition and stored properly, its life can be extended and its content enjoyed for many years.