In his dictionary of the Arts, Dr. Ure says:—“Various menstrua have been proposed for the purpose of expediting and improving the process of tanning; among others, lime-water and a solution of pearlash; but these two substances form compounds with tannin, which are not decomposable by gelatine; it follows that their effects must be prejudicial. There is very little reason to suppose that any bodies will be found, which, at the same time that they increase the solubility of tannin in water, will not likewise diminish its attraction for skin.” Now the very objects here supposed by Dr. Ure to be unattainable, are literally and perfectly accomplished by Hibbard’s method, viz., a menstrum has been found “for expediting and improving the process of tanning,” and that, too, by “increasing at the same time both the solubility of tannin and its attraction for gelatine or skin;” by means, also, so simple, direct and obvious, that it is wonderful that so learned a chemist as Dr. Ure should not himself have made the discovery. But I come now to the principle object in view in this communication. During the experiments and investigations above alluded to, my attention has been directed to two important branches of the manufacture of leather. First. The chemical principles involved in the several processes of making the various kinds of leather, whether it be in “tawing,” as in making kid glove leather, or in oil dressing, as in making buckskin and chamois leather, or in tanning proper, as in making morocco, upper and sole leather. Second. The various species and qualities of the tannin materials used, viz., the bark of hemlock, several varieties of oak, American and Sicily sumac, and terra japonica: these embrace the chief kinds used in this country. It is to this latter—the materials for tanning—that I wish more particularly to call your attention. We greatly need both a qualitative and quantitative analysis of the several kinds of substances used for tanning, especially of the hemlock bark—of the white, black, red, Spanish, chestnut, oak, and other varieties of the Quercus; also of the American and Sicily sumacs, and of catechu or terra japonica. We have many native trees and shrubs, of whose barks an analysis might prove to be something more than mere scientific curiosities. A writer in one of our scientific journals asserts that the bark of the chestnut contains more tannin than oak, and more coloring matter than logwood of equal weights and qualities. On what authority he makes this statement, I know not, but if the fact be so, it should be established and known.