Armstrong Theory established in 1885. It instructs that each one coloring matters could also be delineated by quinonoid structures. And so believed that if a specific compound developed in a very quinonoid type it’s coloured, otherwise it’s colorless. A number of the vital compounds, the coloring properties of which may be explain on the idea of this theory area unit given below. On the idea of this theory we will see that benzine is colorless, whereas benzoquinonesare coloured. However the quinonoid theory isn’t enough to account for the coloring characteristics of all the compounds. as an example, iminoquinoneand di‐iminoquinone, each possess a quinoidstructure even then they’re colorless.