an acid changes the color of litmus paper from blue to red
red is color. correction_fluid is color_other_than_white. red is colour. litmus is acid_base_indicator. blackening is change_of_color. litmus_paper is paper. color_pink has red_and_white_factors change_of_color is change_of_state. whitening is change_of_color. coloring is change_of_color.