I think nitroglycerine is clear.

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Even holy water from the Roman Catholic shrine at Lourdes can’t get by airport security screening passengers for suspicious liquids.

A passenger on a new Vatican-backed charter airline had to hand over a container of water collected at Our Lady of Lourdes Cathedral to security officials at the airport in southern France on Monday before boarding a return flight to Rome, officials for Mistral Air said. They identified the passenger as Italian television personality Paola Saluzzi.

Airport officials barred other pilgrims on the Mistral Air flight from taking holy water from the shrine back to Rome, the Italian news agency Apcom reported. The pilgrims protested that they had waited in long lines to fill up their bottles with holy water from the grotto. [...Snip] MSNBC

Thank goodness that Homeland Security Units are in the Vatican also.