The down and dirty about nerve agents like sarin

In this image taken from amateur video posted online, appearing to show a presumed UN staff member measuring and photographing a canister in the suburb of Moadamiyeh in Damascus, Syria, Monday Aug. 26, 2013, the suburb of Damascus where the Syrian regime allegedly used deadly chemical weapons. AP could not verify the authenticity of the video, but it is consistent with Associated Press reports. U.N. experts collected samples and testimony from Syrian doctors and victims of an alleged chemical weapons attack on Monday following a treacherous journey through government and rebel-held territory during which their convoy was struck by snipers. (AP Photo/MEDIA OFFICE OF MOADAMIYEH) TV OUTWASHINGTON (AP) — Secretary of State John Kerry said Monday that evidence of a large-scale chemical weapons attack in Syria was "undeniable." There are still many questions about chemical weapons, though, some of which can be answered easily and some of which can't.