all your gaseous materials are capable of diffusion through other
materials to some extent..depending on the material. hydrogen is very
explosive in nature...but remember. as with any volatile
substance..proper handling procedures are necessary.
one fact is...americans are programed to fear hydrogen due to the 
heindinburg disaster...but that was caused due to man's lack of
understanding both the gas and the electrostatic discharge of the
dirigible after being in flight for so long generating a.c. current and
throwing a steel cable to a steel mooring mask for docking.
--- Platinum Xpress/Wildcat! v1.2j
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