Looks like they are for masking borders in contact frames;

http://tinyurl.com/5w84sg5 (scroll up in this one for the frames)
http://tinyurl.com/3zhu32p

Yeah, I wouldn't want to store a jar of gasoline in my darkroom either.

The package is probably more valuable than the contents, maybe $5.00 or so in an antique shop, as a guess.