Well...yes & no, really. How old are they...i.e. do you really know? AND do they say "safety film" on them, edge markings etc. You need to make sure you're not dealing with any nitrate based films, before you start trying to do anything with them really. If you're not sure, feel free to drop me a line, there's just too much to get into here, other than to say that if you have an archive nearby--state or fed.--you may want to seek out some advice in the form of a patron request. Try to find one that has a photo conservator, or some type of conservator, on staff. I'm not one--just a museum photographer--but I do handle old negs in my job, printing & duping them. Nitrate negs can be (are) bad news, so take care. Other than just printing an old negative, I would advise just leaving them alone. When they age, they get unstable and unless you know what you're doing, you're likely to do more harm than good. As to what it is, could be anything...could be the film base breaking down, improper storage, bad processing, or all of the above....the worse case scenario would be the base breaking down. Which happens to all films eventually, it's just that the nitrate films & early safety based acetate films, can get really nasty...Anything prior to 1950 (sheet film), that doesn't say "safety" on it someplace, should be suspect...(posted 8410 days ago)this is a good overview site of examples from the Library of Congress, if you want to see some:
http://lcweb2.loc.gov/pp/gendetne.html#Nitrate
Good luck.