▁lead - based ▁comp ounds ▁in ▁k ohl ▁are ▁gal ena ▁( P b S ) ▁– ▁dark ▁grey ▁and ▁gl oss ▁la ur ion ite ▁( ▁P b Cl ( OH )) ▁– ▁white ▁ph os gen ite ▁(( P b Cl ) 2 CO 3 ); ▁cer uss ite ▁( P b CO 3 ) ▁– ▁blue . ▁The ▁ant im ony - based ▁comp ound ▁in ▁k ohl ▁is ▁st ib n ite ▁( S b 2 S 3 ) ▁– ▁blue . ▁ ▁In ▁January ▁ 2 0 1 0 , ▁French ▁research ers ▁reported ▁that ▁the ▁particular ▁heavy ▁eye ▁make up ▁that ▁ancient ▁Egypt ians ▁wore ▁may ▁have ▁had ▁medical ▁benefits . ▁ ▁At ▁subm ic rom olar ▁concentr ations , ▁the ▁spe cially ▁made ▁lead ▁comp ounds ▁can ▁el ic it ▁over production ▁of ▁nit r ous ▁ox ide ▁( N 2 O ), ▁which ▁in ▁turn ▁can ▁trigger ▁an ▁enh ancement ▁of ▁the ▁imm une ▁response . ▁ ▁The ▁ancient ▁Egypt ians , ▁documented ▁in ▁the ▁E bers ▁Pap yrus ▁( ▁ 1 5 5 0 ▁B CE ), ▁discuss ▁these ▁comp ounds ▁within ▁k ohl ▁as ▁protect ive ▁for ▁the ▁eyes . ▁Indeed , ▁k ohl ▁was ▁used ▁an ▁e y el iner ▁and ▁cos met ic . ▁There ▁are ▁a ▁number ▁of ▁en demic ▁oc ular ▁dise ases ▁in ▁the ▁N ile ▁region ▁including ▁tra ch oma , ▁a ▁ch lam yd ial ▁organ ism ▁which ▁can ▁cause ▁cor ne al ▁sc arring ▁and