PC2K is right about what's in your brain being the msot important.

If you do want to read stuff on hazmat placards, take a look at: http://environmentalchemistry.com/yogi/hazmat/placards/

The colors are the most basic thing for which to look. Next you'd probably look at the numbers of the classes, 2.1 flammable gases for example. Finally, there should be another number that identifies the specific substance. If you saw and number and looked here, below the sport where it says "2004 ERG sorted by UN Number," you might be able to identify something specific:

http://environmentalchemistry.com/yogi/hazmat/erg/ s for