Thanks everyone.

Yes, I'm not terribly concerned quite yet, just erring on the side of caution until I can confirm the film base. Better safe (with the film outside, away from the house) than sorry. But once I started thinking about it, I wanted to learn more about the nitrocellulose film handling, even if this particular film wasn't the nitrocellulose type. So I would have asked the same questions either way.

Now, the reason I'm even contemplating using film this old at all is that it is 9.5" wide roll film, intended for aerial photography, but going to be put to use in an ULF panoramic roll-film camera. The film in this size is very difficult to find, even greatly outdated, and at $300+ per roll for decade-old film, it isn't cheap either. If you need fresh stock, plan on a $10,000 minimum order. I would probably die of old age before I saw any of this film at a garage sale, and even global ebay availability is patchy at best. For experimenting on a budget, camera test rolls, etc, sometimes this old stock is the best you can get.