For the routine analysis of soil clay fractions in this laboratory, a camera of the type described by Brindley and Robinson (1946) and by Robinson (1946) has proved very satisfactory. In this camera the clay aggregate is mounted on a flat glass slip which may be set at any desired angle to the incident beam.

Oriented aggregates may be prepared by the evaporation or centrifuging of dilute clay suspensions (Bradley et al 1937, Nagelschmidt 1941, Brown 1953) or by pressure (Mitchell 1953), the dry aggregate in each case being cut up and mounted as required. When using a Brindley-Robinson camera, however, it has been found most satisfactory to deposit the aggregate directly onto the specimen slip by centrifuging.

A suitable centrifuge tube, consisting of a body and base-plug turned out of “Perspex” is shown in the figure. The glass specimen slip fits into a depression of its own shape and size machined in the top of the base.