90 BRITISH PLANTS 
Comparison between the Physical Properties of Sand and 
Clay. 
Sand. 
1. Particles large. 
2. Individual air-spaces large; 
total pore-space small. 
3. Cohesion of the particles very 
small. 
4, Firm and gritty to the touch. 
Clay. 
1. Particles small. 
2. Individual air-spaces small; 
total pore-space large. 
3. Cohesion great. 
4. Soft and greasy to the touch 
when wet. 
5. Maximum water -capacity 5. Maximum water - capacity 
small. | great. 
6. Amount of hygroscopic water 6. Amount of hygroscopic water 
small. | great. 
7. Water - retaining capacity 7. Water-retaining capacity 
small. great. 
8. Very permeable to water. |  §. Almost impermeable to 
| water. 
9. Capillarity great. 
10. A wet soil. 
11. A cold soil. 
12. When dry, 
cracks. 
9. Capillarity small. 
10. A dry soil. 
11. A warm soil. | 
12. When dry, is friable and > 
does not crack. 
is hard and 
13. Drainage natural and easy. 
14. A sterile soil, since soluble 
matter is easily washed out of it. 
13. Drainage difficult. 
14. A fertile soil, since it is diffi- 
cult to wash soluble matter out 
of it. 
15. A heavy soil, hard and ex- 
15. A light soil, easy to work. 
pensive to work. 
Chalky soils occupy an intermediate position—in some 
characters more approaching sand, in others clay. The 
best soil is that which, while light and warm, is fertile in 
plant-food, and contains plenty of water, without appear- 
ing wet. No one of the above soils fulfils all these con- 
ditions, but by suitably mixing sand, clay, and chalk 
together a loam is obtained which answers most of these 
qualifications fairly well. 
