small coal shovel and heat in stove to redness. It will be found that
the leaf mould will smoke and burn, and will diminish in amount,
while the sand and clay will not.

=Experiment.=--Take two wide-mouthed bottles; fill both nearly full of
water. Into one put about a teaspoonful of clay and into the other the
same amount of sand; shake both bottles thoroughly and set on table to
settle (Fig. 20). It will be found that the sand settles very quickly
and the clay very slowly.

As the result of our three experiments we will find something as
follows:

Sand is light in color, moist, coarse, not sticky, settles quickly in
water, and will not burn.

Clay is darker in color, moist, very fine, quite sticky, settles
slowly in water, and will not burn.

Leaf mould or humus is very dark in color, moist, very fine, slightly
sticky, and burns when placed in the fire.

=Experiment.=--We now have knowledge and means for making simple tests
of soils. Repeat the last three experiments with the garden soil. We
will find, perhaps, that it is dark in color and some of it burns away
when placed in the fire, therefore it contains organic matter or
decaying vegetable matter or humus, as it is called. This sample has
perhaps fine particles and coarse particles; part of it will settle
quickly in water while part settles very slowly, and it is sticky.
Therefore we conclude that there are both clay and sand in it. If we