This circular outlines briefly the history of writing inks, in particular those of the iron gallotannate type, gives formulas for a few of these inks and for three iron gallate inks, discusses the aging of writinig, the restoration of faded writing, the freezing of inks, and the effect of inks upon paper. After this come short discussions, with formulas, of other kinds of inks, including colored writing inks, drawing, stamp-pad, recording-instrument, and others. Printing inks and others that depend upon pigments for their color and their special properties are in a class by themselves, and little is said about them in this circular. The methods of testing given in the Federal specifications for inks are described. Then follows an appendix in which are sections on weights and measures, with conversion factors, on equipment for making ink in the home, and on dyes suitable for making inks. Finally, there is given a short list of selected literature references. -- CCI