[koyasha]

Thanks a lot, James!

This whole thing is still a bit confusing, I've never worked with mercury, so I prefer the Noogleberry recommendation of the 5 inch/12cm maximum, I didn't know that. That sounds much better than 2cm. But thanks a lot for explaining!! Just one more thing (out of interest), if I did the same with water instead of mercury, there would be no vacuum, what's so special about mercury? When you say a vacuum at the top of the tube, are we talking about the open side (which is at the bottom after turning it upside down)? Just out of curiosity