The investigations on clays progressing at the Macaulay Institute are fundamentally connected with pedological studies. The general aim of these investigations is to provide evidence which we believe will give us a better insight into the fundamental differences between the soil types as mapped in the field and provide us with an explanation of certain of their characteristics and properties. Within the last year a systematic investigation has been commenced into the clay minerals associated with each different soil type in Aberdeenshire. The methods being used are X-ray examination and differential thermal analysis. A brief account of the X-ray work has been given by Mr G. F. Walker.