=Experiment.=—­Take four student-lamp chimneys. (In case the chimneys cannot be found get some slender bottles like salad oil bottles or wine bottles and cut the bottoms off with a hot rod.  While the rod is heating make a shallow notch in the glass with the wet corner of a file in the direction you wish to make the cut.  When the rod is hot lay the end of it lengthwise on the notch.  Very soon a little crack will be seen to start from the notch.  Lead this crack around the bottle with the hot rod and the bottom of the bottle will drop off.) (Fig. 23.) Make a rack to hold them.  Tie a piece of cheese cloth or other thin cloth over the small ends of the chimneys.  Then fill them nearly full respectively, of dry, sifted, coarse sand, clay, humus soil, and garden soil.  Place them in the rack; place under them a pan or dish.  Pour water in the upper ends of the tubes until it soaks through and drips from the lower end (Fig. 22).  Ordinary sunburner lamp chimneys may be used for the experiment by tying the cloth over the tops; then invert them, fill them with soil and set in plates or pans.  The sand will take the water in and let it run through quickly; the clay is very slow to take it in and let it run through; the humus soil takes the water in quite readily.  Repeat the experiment with one of the soils, packing the soil tightly in one tube and leaving it loose in another.  The water will be found to penetrate the loose soil more rapidly than the packed soil.  We see then that the power of the soil to take in rainfall depends on its texture or the size and compactness of the particles.

If the soil of our farm is largely clay, what happens to the rain that falls on it?  The clay takes the water in so slowly that most of it runs off and is lost.  Very likely it carries with it some of the surface soil which it has soaked and loosened, and thus leaves the farm washed and gullied.

What can we do for our clay soils to help them to absorb the rain more rapidly?  For immediate results we can plow them and keep them loose and open with the tillage tools.  For more permanent results we may mix sand with them, but sand is not always to be obtained and is expensive to haul.  The best method is to mix organic matter with them by plowing in stable manures, or woods soil, or decayed leaves, or by growing crops and turning them under.  The organic matter not only loosens the soil but also adds plant food to it, and during its decay produces carbonic acid which helps to dissolve the mineral matter and make available the plant food that is in it.

Clay soils can also be made loose and open by applying lime to them.

=Experiment.=—­Take two bottles or jars, put therein a few spoonsful of clay soil, fill with water, put a little lime in one of them, shake both and set them on the table.  It will be noticed that the clay in the bottle containing lime settles in flakes or crumbs, and much faster than in the other bottle.  In the same manner, lime applied to a field of clay has a tendency to collect the very fine particles of soil into flakes or crumbs and give it somewhat the open texture of a sandy soil.  Lime is applied to soil for this purpose at the rate of twenty bushels per acre once in four or five years.