Distinguishing Canada Centennial 25 Cent 1867-1967 Types

Just a blind guess here, one is the 80% silver and one is 50% silver.

I have read on a silver stacking site where this guy using some sound recording technology... he can drop a quarter onto a surface and the 80% one actually will graph a bit different than the 50% one...

Other than that.. the only other way is a silver purity test...

I would just assume it's 80% and call it good. :)

Try balancing the coin on a knuckle (or your fingertip, make sure your finger is clean) and tap it with another coin, ideally with a similar weight (because if it's too small the sound will be too soft, if it's too large you'll just knock the balanced coin down). Do the same with two quarters you know are 80% silver and 50% silver as controls. Notice that the sound of the 50% will be higher. Your coin will sound like either one, and the one with the same sound has the same composition %.

Or maybe you can ask wert. He uses a software called Audacity to determine the composition of coins. I couldn't get it to work, so I can't really halp you with this one.