It is pointed out that the distribution of color in a sediment is as important in determining the general color effect as is the total amount of coloring matter present. It is shown that quartz will become iron-stained only in the absence of more active adsorbants, that orthoclase acquires iron stain more readily than quartz, and that while Al(OH)3 is a good adsorbant of iron, pure kaolin will adsorb but little unless activated by some such substance as the alkali carbonates. The iron content of clays up to about 5.0 per cent Fe2O3 is shown to be a linear function of the alkali content, the equation \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage{wasysym} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document}$A=\frac{10\ B-4}{7}$\end{document} where A = percentage of Fe2O3 present and B =...