The active coloring principle in Henna was called lawsone by Tommasi, who isolated it in 1916 and determined its chemical construction to be 2-hydroxy-1, 4-naphthoquinone, C10H6O3. Further definitive work on henna and lawsone was done by h. E. Cox. The extract is an orange-red dye, readily soluble in water, dilute alkalies and acids. The true color can be seen best on white hair. Actually, its coppery, carrot-red shade is the same on all hair of any shade, but it seems to impart different colors because of variation in the basic shade. The color of Henna is developed best in an acid medium.Henna contains a chemical molecule called lawsone. Though the molecule is colorless by itself, but when exposed to sunlight or air it gets converted to a new compound that has a reddish shade.