If it's what I think it is (
http://www.highsidechem.com/solderlene.html), it's made of zinc chloride and ammonium chloride, which is what would be used for things such as plumbing.
Do not use this type of flux chemistry for electronics (will cause corrosion in your joints, and can damage unprotected traces). Use a Rosin based or No-clean organic flux instead (water clean will cause corrosion if not cleaned off in time <measured in hours>, so I'd stay away from this as well).