A salty puzzle

When last we left our intrepid post-Apocalyptic explorer, he was deep in the middle of Fish Week (aka Freshman Orientation) at the local U. We decided to check out a large crate:

Aha! NaCl, what could that possibly mean ... apparently it's the kind of thing you don't have to know, you just have to be perceptive enough to figure it out. Somehow. Luckily we roll a 6 on the Idiot-O-Meter, clearing us to:

Hey, it's salt, everybody! Who knew that NaCl was salt?! Well, we can certainly see the value of a college education, that's for darn sure. I bet behind the door is shelf after shelf of tequila and margarita glasses! Our choice at this point is to either head back to the caravan with our ill-gotten goods, or move on to checking out the door. Given the tenor of our last debate (aka "Pillage Everything"), I'm going to skip ahead and decide to check out the door:

Oooo, a puzzle! How exciting! Given this universe's amazing ability to intuit scientific information just by looking around, hopefully the answer will just come to us, BAM. I'll wait.


OK, not so much. Dang. Looks like we'll have to figure this one out ourselves. Take a crack at it and leave your best guess with your reasoning in the comments. Maybe when we get enough that seem reasonable we'll put it up to a vote. Put on those Santa-shaped thinking caps, folks!