Seems some Destructive Devices were found in the hands of Occupy Portland attendees and I don't mean the police. Found mention at Geek Warrior, leading to good old, Mencken-echoing Bob Owens.
Closer reading reveals something other than a World War (I, II, the fizzling/cold continuations) "pineapple" or "potato masher:" a powerful firework in a home-canning jar, a sort of poor man's jam tin grenade.
Nasty stuff, if the charge is powerful. I'd suspect the old-style zinc or modern two-piece lid (if used at all) would limit overpressure but even a little bit of broken glass headed your way at speed is no fun.
Of course, some True Scotsman had to pipe up, "You don’t understand. OWS is a non-violent protest. Therefore, any protester that commits violence is NOT part of OWS." No, you don't understand: if you want a protest to be non-violent, you have to step up and keep it that way. You can't just say, "Okay, sure, they slept in our camp and stood on our side, but they're Off The Christmas List." It takes actual skin in the game. Or did you miss the row of Occupiers Elsewhere kneeling and arm-linked in the street, defiantly being tear-gassed? Y'know what? They brought attention to their cause. I might think they're ijits but they sure got word out, and nary a bomb thrown.
But back to our story. Bob worries the shrapnel from such a device might be invisible to X-rays.* The answer is, yes and no: "Almost all glass is visible on plain x rays, but small fragments, between 0.5 and 2.0mm, may not be visible, even when left and right oblique projections are added to the standard posterior-anteroir and lateral views. Any patient who complains of a foreign body sensation should be assumed to have one even in the face of negative x rays."
These glass-bombs are both nasty and clumsy. Such a device either has to be gently placed (like a timed-fuse land mine), or thrown with the fuse timed so that ignition occurs before it hits and shatters the glass, which would greatly reduce the effect. It's nearly as dangerous to the user (and his nearby fellows) as it is to the target -- if it works at all. It's the kind of thing a bloody-minded fool would dream up.
Occupiers, if you really wanna be non-violent, police your own. Remember, if the cops pepper-spray or tear-gas you, you get press and you'll recover. When it comes down to thrown rocks vs. hickory sticks, Molotov cocktails against rubber bullets -- or real ones, both sides look bad, people get hurt or killed and you are probably not going to get the benefit of the doubt.
...Compare and contrast to TEA Party protests or the Glenn Beck 9/12 rally; Occupiers and other lefties can wrinkle their noses all they like, but the protest-with-signs Right's average lice-and-bombs score is hugely lower than that of their counterparts. The cleaner campers of Occupy Lancaster are gonna have to work overtime to get their peers caught up.
* Thanks to an ill-considered High School Physics project, I have had the chance to make and read my own X-radiographs of inanimate objects. It's density-based and glass is a bit denser than most of you. (X-rays of the sort you can create with fairly common lab items -- a spark coil and the right kind of radio tube -- will expose the single-shot Polaroid films once pretty commonly found among basic physics lab toys. Alas, we were short on lead and had to use rather more air instead, marking a very large circle on the classroom floor. It proved unpopular.)