SOIL 35 



same size? Does there seem to be any decayed vege- 

 table matter in the soil ? What is the color of the par- 

 ticles? Are they all of the same color? 



2. Small samples of soil may be spread out in a 

 thin layer on white paper and further examined with a 

 magnifying glass. 



3. Thoroughly dry a sample of fine sand without 

 lumps, and fill a water-tight tin can with it. Fill 

 another can of exactly the same size with loam pre- 

 pared in the same way. From a graduate 1 pour water 

 on the sand, allowing time for it to soak in. Soon the 

 sand will have absorbed all the water it can hold, and 

 the level of the water will be even with the surface of 

 the sand in the can. What has become of the water 

 which you poured onto the soil ? How much water have 

 you used? Now do exactly the same thing with the 

 loam soil and compare results. Which soil has more 

 pore space? 



4. Fill three soil tubes 2 respectively with fine dry 

 sand, clay, and loam. Set the filled tubes in separate 



1 A graduate may be made by ruling lines one-eighth inch apart 

 on a strip of paper and pasting the paper vertically on a glass 

 tumbler. 



2 To prepare soil tubes : Take some tall glass bottles, wrap a 

 cloth wrung out of cold water around each about half an inch 

 from the bottom, and place the bottles on a hot stove. The 

 sudden expansion of the bottom will usually break it off even. 

 Smooth the edges with a file or on a grindstone. Plug the neck 

 of each bottle with cotton, and turn it upside down. A rack for 

 holding these tubes in an upright position can easily be made by 

 nailing slats or stretching wire or strong cord across the top of a 

 small box. Compact the soil by tapping the tube gently on the 

 table. 



