Show zinc causes paint to show color variation A mans puzzlement over a fence post which he had pointed painted black but which turned white every nights night was point ota ofa program of research has culminated in 0 o the discovery of 0 a number of chemicals having this remarkable chameleon chamel cham elew edn like property scientifically termed photo apy information regarding i these chemicals has now been beell made publio by tile american Cherni calso society the farious fance post was painted with a pigi pigment nent having a zinc basis it would arn black awon BH OD after sunrise sunrise eael each morn ii g only to turn white again when alu n darkness darlings carve came many explanations have been glen far or lb the e phenomenon but taj ts are not yet agreed as to the cause of 0 lt it they have hn however wever found sev beital other besides the zinc sulfide which was waa in the paint on the hie past post thit that will also change color with will the I 1 light most of the known photo liquids are solutions of chilor lets derivatives of certain dyes the solutions are practically colorless in tia lark dark outturn but buta turn the color of tile parent dye when aposen to light |