THE ELEMENTS OF SOILS. 69 



think there is not enough phosphorus in the soil, we 

 must put some in it. Where shall we get it ? We can 

 buy pure phosphorus by paying a very high price for 

 it, but it would all burn away long before the plants 

 could find it. We look about to see if there is any 

 thing that contains phosphorus. The chemist tells us 

 this element is in bones. Bones can be used ; and 

 we get a quantity, grind them up fine so that the plants 

 can find them easily, and sow the white dust over the 

 field. The plants find the phosphorus in the bone- 

 dust, and attack it greedily, and produce a bountiful 

 harvest. Thus, by knowing the elements, we are able 

 to find them in various things, and can place these 

 things in the soil, and thus supply the plants with the 

 very elements they need. Thus we see it is well to 

 make the acquaintance of our friends the elements, 

 though we may never be able to find them alone or in 

 a pure state. 



We might ask now why we may not continue our 

 observations and experiments, and find out by analysis 

 just what elements are in any particular soil. Our 

 experiments have shown us that soils vary greatly in 

 the amount of organic and inorganic matter, sand, or 

 clay they may contain. May there not be an equal 

 variety in the amount of the different elements in 

 different soils? There is the greatest variety; and 

 analysis will tell us what elements are abundant, and 

 what elements are scarce, in any particular sample of 

 soil. Observe, that in our experiments we have been 

 using only small samples of soils. Even a whole peck 



