Excerpt from Behavior of Synthetic Tanning Materials Toward Hide Substance The various synthetic tanning materials vary very much in the ex tent oi their solvent (hydrolytic) action on the hide substance of leather during tanning, some showing negligible hydrolysis in solutions of normal acid concentration, while others, in solutions of half this concentration, produce a practically complete destruction of the leather as such. N o relation has yet been found between this behavior and other characteristics of the syntans. As regards the fixation of the tanning material in the hide, the syntans may be divided into two groups corresponding to the two general methods of preparing these products. Those which are obtained by first sulphonating an aromatic compound and then condensing the sulphonic acid with an aldehyde (designated as type A syntans) combine with the hide rapidly, but to a limited extent, and the maximum of combined tanning material, as well as the time required to reach this maximum, are but little affected by the concentration of the solution. The second group of syntans, in the preparation of which the order of sulphonation and condensation with aldehyde is reversed (type B) possesses much greater filling power, requires longer time to reach a maximum, and the time required to reach this maximum is more dependent on the concentration of the solution. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.