Excerpt from Action of Sodium Sulphate in Synthetic Tanning Materials It therefore follows that if a hide is treated with a solution contain ing both sodium sulphate and a synthetic tanning material (which is usually an active acid) both the sulphuric acid and the tanning material will combine with the hide to a certain extent. In other words, the neutralization of the excess sulphuric acid ln syntans, by means of sodium hydroxide or any other reagent 'which yields a soluble sulphate, does not entirely prevent the sulphuric acid from reacting with the hide during the tanning process. The extent to which the sulphuric acid and the synthetic tanning agent will combine with the hide under these conditions is not yet definitely known, but it is probable that an equilibrium will ultimately be reached, depending partly on the nature of the syntan and partly on the concentrations of the reagents in the tanning solution. But whatever the amount of the sulphuric acid which will be combined ln the leather, the results obtained in the present study indicate that this can not be com pletely removed by any amount of washing with water at ordinary temperatures. It is possible and even probable that this combined sulphuric acid which remains in the leather after thorough washing will have no injurious effect on it, but this still remains to be definitely ascertained. In any case, thorough washing of the leather after using a syntan which contains any considerable amount of sodium sulphate or other soluble sulphate is always necessary in order to prevent injury from the free sulphuric acid which would result from the inter action of the sulphate with any excess of uncombined sulphonic acid. 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.