The specimen which formed the subject of the first of the following analyses, was brought from the banks of the river Dee, about seven years ago, by my friend Mr James Mill, who at that time resided in Aberdeenshire. By him I was informed, that considerable quantities of it are found in different parts of the bed of that river,—that it is called by the inhabitants ironsand,—and that they use it for sanding newly written paper. I tried some experiments in the year 1800, in order to ascertain its nature; but was too little skilled at that time, both in mineralogy and practical chemistry, to manage an analysis of any considerable difficulty.