Abstract

In Parts I and II, of this series, comparative kinetic studies of the co-ordination of trivalent chromium ions to acetate radicals, hide powder and pelt pieces were reported, In order to determine the effect of olation on the reaction rate, the study was extended to a parallel series of reaction solutions prepared from boiled and aged chromium nitrate solutions. Differential effects were found to be small in the case of chromium nitrate solutions boiled and aged at O basicity, indicat ing that structural changes induced by boiling and ageing at low basicity were slight. Co-ordination studies using previously boiled and aged 334-% basic chromium solutions gave evidence of an enhanced reaction rate in the case of chromium nitrate and a reduced reaction rate in the case of chromium sulphate. Comparative miniature tanning studies showed that boiling and ageing of chrome solutions prior to reaction served to enhance the initial rate of chrome fixation.