Click here  This is very odd and shouldn't be happening. I have no clue why the Mercury hasn't evaporated, then condensed around the inner side of the cfl. My guess is there to much mercury, and the plasma can't evaporate it all. This cfl works perfectly fine, but there seem to be to much inside, as you can see a P size mercury ball.   

That's almost the quantity of a mercury lamp!    Is it brighter than normal?

I'd imagine you'd have to operate it at higher pressure/temperature to get all the mercury to evaporate. And then lumen output would actually decrease because the brightness of a fluorescent is mostly due to phosphor excitation by the UV light produced by the low-pressure arc. The lamp would probably look greener, more like a coated high pressure mercury vapor lamp.

I don't actually think that this is a problem.  Years ago, when fluorescent tubes had normal amounts of mercury in them and before they were labeled with an (Hg) symbol, it was normal for a tube to have a little ball of mercury like this in it.  I had a 22 watt Circline bulb that I bought in 1984 that had the same thing in it, and it lasted until 1993!

Fluoros are saturated-vapor style, so the pressure is controlled by the coldest-spot temperature. So the extra mercury will not evaporate and work only as a reserve (so this lamp most likely do not end as mercury depleted... :-)). I've seen this often on newer lamps, but the ball disappeared after some hours burned... But it might be, then there was not enough binding component in the amalgam mix, so that's why the mercury form such ball (instead of resting in the designed amalgam reservoir). Or the lamp was operated in some CFL-unfriendly luminaire (what a surprise ), so the coldest spot formed somewhere else then designed, so the mercury was distilled out of it's original resting place