"The third sort of soil which we farm people have to deal with is lime soil. Remember we are thinking of soils from the farm point of view. This soil of course ordinarily was formed from limestone. Just as soon as one thing is mentioned about which we know nothing, another comes up of which we are just as ignorant. And so a whole chain of questions follows. Now you are probably saying within yourselves, how was limestone first formed? "At one time ages ago the lower animal and plant forms picked from the water particles of lime. With the lime they formed skeletons or houses about themselves as protection from larger animals. Coral is representative of this class of skeleton-forming animal. "As the animal died the skeleton remained. Great masses of this living matter pressed all together, after ages, formed limestone. Some limestones are still in such shape that the shelly formation is still visible. Marble, another limestone, is somewhat crystalline in character. Another well-known limestone is chalk. Perhaps you'd like to know a way of always being able to tell limestone. I'll drop a little of this acid on some lime. See how it bubbles and fizzles. Now Albert will drop some on this chalk and on the marble, too. The same bubbling takes place. So lime must be in these three structures. One does not have to buy a special acid for this work, for even the household acids like vinegar will cause the same result. Albert will prove this to you. "Then these are the three types of soil with which the farmer has to deal, and which we wish to understand. For one may learn to know his garden soil by studying it, just as one learns a lesson by study. "I believe the boys from their last winter's work feel fairly familiar with soils, I have in these three tumblers the three types of soil. As I pour water on them just see what happens. Observe how little water it takes to saturate sand. The limy soil holds more water and the clayey an amazing quantity. "I do not know whether you are much acquainted with the sea shore, I doubt it." "I am," broke in Katharine, "for each summer, except this last one, I have spent a month at the beach." "Then possibly you can tell us, Katharine, whether, or not, the sand takes in, or absorbs, much heat during the day." "Indeed it does absorb heat; why some days we used to go barefooted on the beach right after dinner. I can tell you there were times when we couldn't stand the heat of the sand."