In Lassaigne’s test for nitrogen, the Blue color is due to the formation of

When nitrogenated lassaigne’s filtrate is treated with freshly prepared ferrous sulphate solution and dilute sulphuric acid will give Prussian Blue.Na+C+N→fuseNaCNFeSO4+2NaOH→FeOH2+Na2SO4FeOH2+2NaCN→FeCN2+2NaOHFeCN2+4NaCN→Na4FeCN63Na4FeCN6+4Fe+3→Fe4FeCN63+12Na+                                                                 Iron(III) hexacyano ferrate(II)