(1) Removal of chlorine ions by soil from dilute hydrochloric acid solution has been shown to take place under the experimental conditions employed.
(2) Interaction between dilute acids and soil (free from carbonates) has been studied. The results show that hydrochloric acid, nitric acid, sulphuric acid, acetic acid, citric acid and phosphoric acid all react with soil. The state of equilibrium between the soil and the acid solution can be satisfactorily expressed by Freundlich's equation. The order of reactivity of the soil towards various acids does not follow any obvious rule.
(3) The various soil fractions do not show any fundamental difference in their equilibrium relationship with regard to an acid solution; the order of their power to react with acid following inversely the order of the size of particles in them.
(4) The experiments recorded seem to support the view that the interaction between soil and acids is a surface phenomenon.