58 THE ESSEX NATURALIST.
Interesting confirmation of the fact that the relatively
coarse mixtures of clay and sand in use at the brickfield at
Buckhurst Hill tend to produce products more or less uniform
in density is afforded by the results of some experiments kindly
made at my suggestion by Dr. Rudolph Lessing, who has been
most generous in his assistance. The results are embodied in
the following Table :
French's Brick-Earth. Fired in a Gas-Muffle.