Adhesives are usually regarded as ill-defined substances of a colloidal nature, typified by glues, gums, resins, pastes and the like. It is the object of the present communication to show that pure substances can fully rival many of the common adhesives. In a very recent paper, Sir William Hardy and Miss Nottage have described very interesting experiments on the normal force required to detach completely a cylinder from a plate when the cylinder is standing in a pool of liquid on the plate. The forces required ranged from about 1 gram to over 110 grams for a cylinder 1 cm. in diameter—that is, up to 2 lbs. per sq. inch. The work of Budgett on “wringing” together optically plane steel surfaces with a trace of liquid or grease between could produce adhesion amounting to about 40 lbs. per sq. inch. The present paper will show that pure crystalline organic chemicals will produce joints between optically polished metal surfaces whose breaking strength may approach a ton to the square inch.