BNSL IS BLACK CORROSIVE VESICCANT LIQUID WHICH CAUSES PAINFUL BLISTERS ON THE SKIN. IT CONTAINS ABOUT 46% OF A CATECHOL DERIVATIVE, BHILAWANOL HAVING LONG UNSATURATED CARBON SIDE CHAIN (C15H27). THE REST OF THE LIQUID IS MOSTLY A TARRY MATERIAL COMPOSED OF HIGH BOILING PHENOLS AND HYDROCARBONS. ON HYDROGENATION OF BNSL(B.P.213-214), HYDRO-BHILAWANOL IS ABTAINED IN THE FROM OF SILKY – NEEDLES HAVING M.P. 57-58.THE RECENT STUDY BY RRL ,HYDERABAD,ON THE CONSTITUTIONAL MAKE UP OF BNSL BY NMR TECHNIQUE SHOWED THAT THE DIENE CONCENTRATION OF BHILAWANOL IS ABOUT 70 PERCENT.