GREEN edged flame occurs due to formation methyl borate B' is `B(OCH_(3))_(3)` On brinding the PASTE of borax `+CaF_(2)` and conc. `H_(2)SO_(4)` close to a bunsenflame, imparts green colour to the edge of flame Borax gets hydrolysed into boric ACID in acidic medium and then form ester of methyl borate with methyl alcohol.