Vacuum 'leaking out'

Helium is a very small molecule (jist one atom, and a smal latom at that) and will difuse through glass I think. It'll certainly get trhough any margine seal. This reminds me of one of the most elegant physics experiemtns I read about. THere was an evaculated vessel containing an alpha spurce and a thin-walled evacuated glass tube with a couple of electrods sealed in it. The alpha particls collected a couple of electrons (aince the source was originally electriclal neutral, there must have been 2 spare electrons for each alpha particle), then the result diffused through the thin-walled glass tubve. Afte a tibe, a hig votlage was applied between the elctrodes and the gas in sie the tube, formed fro mthe alpha particles which had ffiused in, ioniese. The spectrum of the light thus produced was identical to that of helium. Thus showign that the alpha particle was a helium nucleaus (as had been suspsected from the measured charge/mass ratio before this experiment). I think with suifficient pressure (the more the merrier, provided it doesn't crus hthe laser tube) and time it will work. -tony