During a Jan. 20 interview, Scott A. Boley, of Narvon, told troopers he possessed homemade explosive devices, charging documents said. Boley told police he would order ingredients online, such as potassium perchlorate and aluminum powder, which create “flash powder” when combined. Flash powder is a fast-burning mixture that makes a blinding flash of light and a loud noise when ignited. Boley told troopers he would combine the ingredients and make bombs, according to the affidavit. His preliminary hearing in Chester County is scheduled for Feb. 2.