The methods of extraction of free sesquioxides in soils are discussed. Using aluminium foil and ammonium tartrate, the readily soluble sesquioxides are removed from soil profiles and the resultant mechanical analyses are compared. Differences between iron oxide content and titanium oxide content of treated and untreated silt and clay fractions, show that there is more readily soluble material in the surface horizons and this is related to the power of humus to render soluble these relatively insoluble materials. High iron oxide content and titanium oxide content of deep horizons are believed to be due to leaching of parent rock, with consequent removal of alkalis and subsequent elevation of the sesquioxide percentage. The processes of translocation of iron and titanium are discussed.