Which chemical weapon was used in Syria? Here’s what investigators know.

Three conventional bombs came first, dropped from the belly of a Syrian army jet near the town of Khan Sheikhoun in Syria's Idlib province. They exploded, releasing plumes of black smoke into the sky. Then there was a fourth, one that made almost no sound on impact. The only indication that it had fallen: a cloud […]

Source: http://www.washingtonpost.com/blogs/worldviews/wp/2017/04/06/which-chemical-weapon-was-used-in-syria-here-are-some-clues/